Introduced in 1973, the Grabber was Gibson's first bolt-on neck bass and featured a sliding pickup (you "grabbed" it to change the pickup position, hence the name). I originally thought that the natural satin finish, introduced in 1975 and seen in this well-known footage from San Fransisco 75.01.31, was Gene's first which was later re-finished but he actually had two Grabbers on the road with him and he used both during the Winterland show.
The reddish metal flake Grabber appears at the Midnight Special taping on 75.04.01 where we get a fairly close look at the almost matte finish (and a taste of the obvious sonic qualities it possessed).
The reddish metal flake Grabber first shows up in Fayetteville, NC on 74.11.30 but it doesn't see steady action until 1975. "[The Grabber] was a well built instrument that weighed a ton, [...] the body was too big and I couldn't move as easily with the thing. [...] I had two of them on the road with me, but I liked the sound of the off-red one." [*] The reddish Grabber was re-finished since Gibson never offered the Grabber in any kind of metal flake finish. In fact, in 1974 it was only offered in ebony and wine red (a high-gloss, see-through finish that looks nothing like this bass). Considering the photographic evidence the natural finish Grabber doesn't seem to have gotten much action.
An interesting aside is that the Grabber was the least expensive instrument in the Gibson 1975 catalogue, even cheaper than the Marauder that Paul smashed on a nightly basis.
But, far be it from Gene to play an off-the-rack bass in standard configuration for long. This is where Gene's search for something very specific seems to start. No matter what Gene may say in various interviews, the various instruments he's tried and modified over the years all point to him wanting a simple, no-frills instrument. So, after a few short months in "the rotation" it is modified by removing the tone pot and moving the output jack up in its place. Here we see the original two-knob version on the far left and a few pics of the modified one-knob version. Earliest known appearance of this version is 75.05.06 in Milwaukee, WI.

Modifying a low-end bass didn't work out for Gene and after taking center stage on the front cover of Alive! the Grabber was used sparingly until the last known sighting at Cadillac High School on 75.10.09.
The Ripper was introduced as the "big brother" to the Grabber in 1973. It was a stab at the more affordable market then dominated by Fender so it was a straight-forward instrument without fancy inlays and with controls and pickups mounted on the scratchplate. The '73 and '74 models were slightly "rounder" over the horns and had a slightly wider body so considering the look of Gene's Ripper it was probably a 1975 ebony version which sported an alder body (Gibson reverted back to maple in 1977). The first known sighting of this bass is on 75.08.09 and it doesn't seem to survive 1975. In the end the long-scale neck and the rather elaborate Q-system electronics probably proved unnecessary for Gene's no-frills style. Chances are Gene just took the opportunity afforded him by the Gibson sponsorship the band enjoyed at the time (see the back of any KISS album from the time) but found that the basses weren't to his taste.
The Q-system was designed by Bill Lawrence and was quite versatile. So much so that Gibson put out a demo vinyl record showcasing the various tones the system was capable of.
One of the least used basses in Gene's arsenal, the Gibson Les Paul Triumph doesn't appear in any live photographs from 1976. It is only shown in a series of backstage pics from February or March 1976, a single backstage pic from Stockholm, Sweden on 76.05.28, and a later backstage instrument lineup from Daytom, OH 76.08.08. The instrument is clearly a Triumph rather than the earlier Les Paul bass (the control scratchplate is a dead giveaway) but Gibson only offered it in natural and white finishes which leads me to believe that the instrument in Gene's hands was refinished.
Long believed to be a prototype for a possible Gibson Gene Simmons signature guitar, this bass is actually a heavily modified 60's Gibson EB-0. Exact year is unknown but Gibson transitioned to this body type in 1961. It has a 30½" scale which matches that of the LoBue. As for the modifications, it has been refinished and there's additional binding not on the original; under the bridge cover is a Leo Quan Badass bridge with the strings loading through the body via added string ferrules; a ca. 1970 replacement Gibson pickup has been added and moved closer to the bridge; and a new, custom shape pickguard has been added.

This bass appears to have been a backup in late '76 to early '77. It makes its first known appearance in Cleveland on 76.09.03 towards the tail end of the Summer Tour '76. It logged serious high-profile time when it was used for the taping of both the Paul Lynde Helloween Special in late October and the promo videos for Don Kirschner's Rock Concert in November. After a brief run during the '76-'77 Winter Tour it makes its last known appearance in Tulsa on 77.01.06.
The technical info on the EB-0 is taken from the January 2007 issue of Vintage Guitar (also avilable online)
The Gibson Thunderbird was a backup used on occasion when the trusty Spector #1 had to take a rest. After being on a breif hiatus the Thunderbird returned to the Gibson catalogue in 1976 for the Bicentennial. Gene's version is either a '76 or '77 ebony version that was modfied from the get-go. First off there is no Thunderbird logo visible in the few pics showing the white pickguard version which means that it's probably a replacement. The pickup cover has been removed and the original Thunderbird humbucker it covered has been replaced with a larger humbucker (probably a DiMarzio since Gene were fond of those and happened to know Larry DiMarzio from school). There is no evidence of the Thunderbird actually being used on stage during the Love Gun tour but for the Alive II tour it shows up in a limited number of pictures.

It does, however, get a second incarnation with a mirror pickguard and this version features prominently in two video sources from the day. It is used extensively during the show in Largo 77.12.20 and it is also featured in the "imposters" live scene from KISS Meets the Phantom of the Park. (All the mirror pickguard pics below are from the mock show in Valencia for the movie.) It is gone from the lineup in 1978 as the second Spector comes in as a backup.
My theory is that all of these (with the exception of the already heavily modified EB-0) were endorsement instruments that were either pure backups or ones that Gene tried to make into his kind of bass. Since neither of the Gibson basses worked out, even though Gene certainly tried to honor the endorsement for the better part of 1975, I think it's safe to assume that long-scale basses (only the EB-0 and the Triumph were short scale) weren't to Gene's liking at the time.
(The Thunderbird plays one final role in this story but not until 1992. When KISS did their first "European" tour in 4 years they stopped by a TV studio in Hilversum, Holland on May 29 to record singback versions of Unholy and God Gave Rock 'n' Roll To You II for the show Countdown. For this occasion Gene borrowed a Thunderbird and proceeded to "thumb" his way through the songs.)
There is a photo as early as 77.08.19 in San Diego, CA that shows the white pickguard Thunderbird on stage during the pre-show setup.

There are also photos from Atlanta, GA 77.12.30 that show the mirror pickguard version standing by the side of the stage awaiting use.
[*] 1996 Guitars that Rule the World, Metal Edge presents KISS Alive!

The move to Gibsons during 1975 was purely financial. Larry Harris had set up an endorsement deal which apparently specified that the band use Gibsons exclusively on stage in exchange for free instruments (see And Party Every Day p. 100).
It's a little hard to say when the Gibson sponsorship ran out but the classic "KISS uses Gibson Guitars and Pearl drums because they want the best" was present on the back cover of Love gun (June) but absent on Alive II (November).
The Les Paul Triumph bass, actually designed by Les Paul himself, had been introduced in 1971 as a successor to the Les Paul bass. Considering the rather complicated control layout, 3 knobs and 4 switches, it was probably not a Gene favorite.
There is a bass resembling the Grabber, based on the headstock, standing offstage in a pic from 76.02.01, in this backstage pic from Portland, OR on 76.02.11, and again in New Orleans, LA 76.03.12, but it's hard to say for sure. It's possible it stayed on as a backup.
Gene brings out the metal flake Grabber for 100,000 years at Winterland. One can see the sparkling of the finish during his blood-spitting routine. Thanks to abusername for pointing that out.
For the show in London, Ontario 74.12.22 Gene poses with the Grabber backstage but plays the LoBue for the show.