Questions on Building the Logistics Tail for Ol John Lee's Driveline Replacement

[Sharps40]

Starting to build the inventory and logistics tail for a complete 2013 driveline overhaul and upgrade on Ol John Lee.

A few questions for experienced folks on here: (I'll add more questions as they come up)

I plan a reman 327 to replace the very tired original 283.

- Am I correct, factory rams horns on the 283 are 2" collector size?

(Seems I have a choice here, new 2" dorman manifolds #674-501 or a slight upgrade to the Corvette style down dump rams horns with 2.5" collectors from Dorman {674-503 and 504} or Wiseco {938-MA035RAW})

- I have the SM318 3 speed, planning to replace with Muncie car M20. What is the output shaft spline count for the SM318?

(yep, I'll verify by yanking the driveshaft but not this week! Pretty sure its the same as the reman M20 I'm looking at but figured I'd ask and delay more grease in my hair for a couple days.)