My BB Mopar has a flywheel / adapter with a 4 bolt drive shaft adapter - if you measure one way the bolt centers are 2 inches across, the other way 2.4 inches

The olds driveshaft / cv joint I have is wider and doesn't fit.

My question is - is the 2x2.4 a common size, and does anyone have one they want to part with?

I could easily be wrong on this but the version that is (roughly) 2" X 2 3/8" is a 1310 style and the larger version is the 1350 style. I've seen many driveshafts for the Olds that the driveshaft and the PTO were one piece, not sure if your Mopar has a one piece or if you have a seperate PTO and a seperate driveshaft...

I feel so ignorant about this stuff :-(

OK, so I think I found what I have - http://www.rexmar.com/page311.html / http://www.rexmar.com/page126.html but no Mopar one is listed.

I see I have the std duty small flange PTO and the heavy duty large flange CV drive shaft.

Any thoughts on who makes a large Mopar PTO adapter? I don't know how long the small driveline would hold up (or are they actually stout enough???)

edit - after rotating the cv around on the pto, I don't know if there is actually a way to make it fit. all 4 of the bolts are the same location (give or take) as the crankshaft bolts itself, and there doesn't appear to be a location where all 4 bolts have enough material to create a hole to thread into.

I will have to either get real creative (like studs, etc), or use the small CV.

Speedy that DL in your pic looks like "Olds specic" 6 3/4  short "rockwell" (doesn't use a seperate PTO) with integral PTO flange (all but obsolete) Old Squirts' right your PTO looks like  a 1350 bolt pattern . 1350DL's  are damn near impossible to get since the last years "restructuring" of Spicer (and spendy $$) for your uses a 1310 should be fine ! PTOs for mopar are available in 6 and 8 bolts and 1310 as well as 1350 OAL for the D/L PTO combo is about 8.5 in     Tom

If the Olds driveline bolts directly to the flywheel, then no, you can't use it. You will either need a 1310 driveline to fit your existing Mopar PTO, or a 1350 driveline and a 1350 Mopar PTO. Unless you are running real big power the 1310 will suffice. The 1310 driveline is easier to find used and new ones cost about 1/2 of what a 1350 costs.