I'm wanting to install a SBC with a TH350 and thinking about a 203/205 combo. Will this be too long for a stock length YJ?

I don't think you're goin to have much luck gettin a doubler to work on a stock wheelbase wrangler.

Unless you have the 203/205 already ,hang an atlas or a worked over dana 300 (4:1 gears) on the back of the t350 .The adapter parts alone for the 203/205 are $770.00 and the same for the 4:1 300 gears .so the 300 makes more sense right there .The cost of the doubler kit plus 2 transfer cases and 2 cross members and skid plating and shifters and down time and headaches ,doesn't sound like its worth it for a YJ ,maybe a M-715 ,with some weight to it .

Obviously the atlas is more yet , but it does more from the get-go ,larger outputs ,5:1 if you want ,and you'll pass it down to your kids .

Think I'll keep with my plan from last year when I was gathering parts. I have a NP208 in the YJ right now, so I'll keep it and run it. I have a Waggy TF727, NP208 in there. I got a shaft to put in the 208 to make it fit with the TH350 for this build and will get a clocking ring to make it fit in the YJ better this time.

Just debated the doubler job since I ended up with a 203 when I got a SBC and the TH350 last year.

You can grab a 208 from a dodge 1/2 ton or ramcharger and put the output shaft and yoke with it's rear extension housing on to your jeep 208 .That dodge 208 is a fixed yoke ,short output (SYE).It'll shorten you up like 5 or 6 inches and leave you with 2.7 low range ,same as a dana 300.

my buddy has that setup in his cj-5. however his rear driveshaft isnt much more that 2 yokes welded together. it took along time to get it dialed in. even the slightest amount of axle wrap would kill his shaft and he had to limit the articulation. it can be done a little easier on a yj but not worth the headache in my book.