All most of those long tailshafts are is a longer output shaft with the bearing and seal moved back inside a case.
Changing the output length could be as simple as cutting out x number of inches out the middle ish part of the shaft then sleeving the 2 pieces inside a slightly inside diamiter tube.
Cheap old school way to shorten axleshafts that is not needed today with how cheap shortened shafts are.
With good clean welds and a bit of time on a lathe you can make a shortened output. Then cut the middle out the old case welding it together while maintaining alignment.
Lots of work. But may be your best option if your up to the fabrication.
Be honest about your skill level here and be willing to mess up/replace some parts to get things right.
Cereal is lost in his cornflakes here.
1st of all, what Sag 3 do you have exactly?
I’ve never seen a modified that a Sag-3
didn’t work in as is. Even those still using a power glide, is still longer than a Sag-3.
2nd, What problem are you having that the trans is too long?
Would you be talking about using the 8” yoke?
What class? Sanction? A-Mod? B-Mod, Econo-Mod? Something other?
The thing is, rules have to make sense on a systemic level.
A $2500 quickchange with a Bert, Brinn, Falcon behind a 400hp junk 602, for $400 to win doesn't make sense. Even if the goal is ease of parts replacement down the road.
There will always be a couple rich guys overspending, and a couple no budget guys ridin around making noise, for the other 90 percent on the local level, A floater, with a Sag 3, will last a very long time and be trouble free,
That said, you can't stop racers from thinking they can buy their way into winner circle. That, is the bigger problem come to think of it.
Elite, Razor, Bandit, Longhorn, Ruhlman, Allen, and other popular names etc........A roller, is in the 35k range and turnkey around the 50k range. all for $400 to win.