I have a 68 chevy II with a 350 and an auto transmission, but I would like to get a new 350 crate engine and convert to a 4 speed transmission. I'm not sure how exactly to do it, and how much cash we're talking. Any Thoughts?
The conversion is actually pretty easy once you have all the parts. It will take a weekend for the inexperienced. An experienced mechanic with all the right tools could do it in 4 - 6 hours.
1. Source a complete clutch pedel/linkage kit for any one of several sources. Classic Industries, Chevy2Only, Modern Preformance to name a few)
2. Source a flywheel (you'll need to know if you have a 2 piece or 1 piece seal engine). Decide if you want a 10.5 or 11 inch clutch to get the correct sized flywheel
3. Source a clutch kit. Don't forget to put the pilot bushing in.
4. Source a bellhousing. You can get these from ebay or new. If you are running an 11 inch clutch, you will need the larger bellhousing. Places like Keisler Engineering make 621 reproduction bellhousings.
5. Find the transmission and shifter.
6. You crossmember will work and
7. I believe the Powerglide and 4 speed are the same length, so your drive shaft should work. (someone please confirm!!!)
The cost will depend on what you find used and what you buy new. With all used parts, you can do it for under a grand.
Edit: I should add, If you install a 4 speed with 27 spline output shaft, your yoke will work. If not, you'll need to put a 32 spline yoke on your driveshaft.