Rist00, hope you didn't click any of kkpp4's links. Looks like malware to me.
Anyway, you've got one of the tougher problems a GT-380 owner or restorer is going to encounter.
The exhaust system, specifically the frame tab for the passenger pegs was extended in what I think was about halfway through the production run. Low enough VIN and the 75 system fits. Higher VIN and it won't. The change in the frame tab required changing the rear mounting of the mufflers.
This one really baffled me because the Japanese simply do not go through the expense of retooling without a darned good reason to do so. In this case there was some retooling for assembling the frame but, more surprisingly, expensive retooling for the comparatively inexpensive exhaust system. And I can't tell that the passenger, which this bike was just barely gutsy enough to handle long enough for a difference to matter, got any benefit.
What you need to do is measure either of your outer pipes from the rearmost part where it mounts to the engine and to the bold on the muffler that goes to the frame or hole in it where the footpeg goes through. Off the top of my head, I don't remember which it uses.
When checking out a system on eBay, ask the seller for this measurement or at least the VIN of the bike the system came from.
When I restored a 76 GT380, I bought a parts bike for it and a loose exhaust system.
Neither fit. The parts bike was a 75, so I knew my problem was my bike was built after the changeover.
So if you find a VIN real close to yours (month of manufacture would help, too), chances are good the system will fit. But the only way to be sure is the measurement I mentioned.
If you measure yours and email the dimensions to me at firstname.lastname@example.org
, I'll measure the spares I've still got and we'll figure out something if we've got a match. Though I suspect you've tried ones and found they don't fit, so likely have an after-change bike, and as you know, the model was discontinued months later, making this a rare part.
Two other helpful bits if you haven't encountered them or for the benefit of other readers.
1. Baffles: Soak the heck out of the threaded part of the retaining bolt with an aggressive penetrating oil. I'm a WD40 guy, but for stuff like this, PB is the only game in town, IMO. You do NOT want to break these bolts. You should also generously spray where the baffle fits into the muffler. The friction fit here because of rust can be a show-stopper. Though it sounds awesome, don't run without properly packed baffles. Without changing main jets, you'll be dangerously lean and holing pistons, to the joy of your annoyed neighbors.
2. A local salvage yard that has more Suzuki GT bikes than anything else seemed to be a goldmine but the bikes were all outside and all hard wheels removed. So they're sitting on the ground right on the exhaust. I found a bike with a beautiful set of chrome expansion chambers, tipped it over, and there was nothing left of them from sitting on the ground.
Good like on what I assume is a restoration project. This is a terribly fun bike.
I got most of the way through mine and sold it to a friend of a friend who made an amazing cafe bike with it.
If this is part of a GT collection you're putting together, you might want to contact me on that, as well. I've got a sweet 76 GT-185 which has become the unobtainable bike of the series.