Remember there are three major differences between 336s out there:
- 336 used in Renault 16: Renault bell housing, 3.7x:1 and ring gear turns the other way.
- 336 used in Europa S1 and S2: Renault bell housing, 3.56:1 and ring gear turns the right way.
- 336 used in early Europa TC: Lotus/Ford bell housing, 3.56:1 and ring gear turns the right way.
Pricing is a matter of luck and availability. $25 at a scrappers for an R16 unit to $1K+. Hopefully you can find what you are looking for in the $200 range.