I can't provide a definitive answer here, but I owned an early 90s TriAxis and used it for recording / touring until about 2001. This model had the original red lead 1 tone. I sold that TriAxis to a studio in LA, and spent the money on a Chapman Stick (no regrets on this... I playing the Stick was my gateway drug to Warr Guitar, which I love!). A few years ago I went into the studio to sweeten / overdub a re-release of one of our earlier live recordings, so I rented a TriAxis and loaded up my presets from an ancient backup. I used the same guitar, and to my ears the LD1 Red was substantially different in the newer version of the preamp. I didn't look up the specific manufacture date or rev # of the rented TriAxis, but it had the dreaded "recto fat" mod, and just sounded muddy in the mix. For a lot of my rhythm tracks I used the "rhythm yellow" mode, and those preset sounded the same to me. I went through all the other modes just to see if there was anything I wanted to use as the basis of tweaking my AxeFX models, but they all seemed like they were unchanged from my original unit.
The very first run of the TriAxis didn't have the recto tone at all. The red lead 1 voice was more like a Marshall. In a revision to the board architecture, Boogie changed the red lead 1 to a "vintage" recto tone with the "fat" mod to enhance the low frequencies. There is also supposed to be a v3 build (pretty recent) that swaps that out for more of a LoneStar tone. I haven't played through one of the newest versions, but I did own a LoneStar for a long time, and that is a very nice amp.
