EDIT when you said 4 speed I assumed manual if so read below. If not ignore.

it should be pretty straight forward; flywheel, pressure plate, clutch disc and associate bolts. Check tech wiki as the A15 crank uses different flywheel bolts than A12.

Also,review tech wiki on the throw out bearing there are different heights; the A15 flywheel is a bit taller / thicker than A12, so you need to have the appropriate throw out bearing.

Note you can use an A12 flywheel as it is lighter than the A15 stock unit (4lbs or so). On a shameless note I have a 14lb A15 flywheel (8lbs lighter) (see the classifieds).

For transmission I'd try and find a 5 speed overdrive unit if you think you'll do a lot of freeway driving. If not just stick a 4 speed in it as they are cheap. I might even have enough parts to put a stock 4 speed together which if I do you can have for free. If you want to drive up to Vegas I have stock A15 flywheel clutch pressure plate etc that you can take as well.

Tom

The 3-speed auto is 3N71B
The 4-speed auto is L4N71B. Same basic type, so upgrades are possible. See L4N71B Swap. As only a few people have done this, there is no full steps guide available

I have a A15 engine with a 3 speed auto box.
Does anyone know if I can change / up grade to a 4 speed box that I can put in without doing to much or change much?