rear main seal

i have never changed one but when it comes to mechanics i can usually figure anything does anyone have any tips or suggestions

I don't know what year your car is, but in 1986 (or maybe a year or two later), Chevy put a 1-piece rear main seal on small blocks, which means the trans. has to come out to change it. If it's older than that, unbolt the motor mounts, raise the engine, and block up the motor mounts. You may need to remove the fan or shroud for clearance. Remove the front exhaust pipe, flywheel access cover, and starter. The oil pan can now slide out under the flywheel. Remove the rear main cap to gain access to the seal. Now is a good time to check the main & rod bearings for wear. Since you're in this far, it makes sense to replace the bearings if they show signs of wear. Make sure to replace them with the correct size (stamped in the back of the bearing).

If it's the new design, remove the trans. and flywheel. It's a good idea to support the back of the engine when the trans. is out. Screwing a couple sheet metal screws into the old seal body will help to remove it without damaging the crank surface.

If you're not sure which engine you have, drop the flywheel access cover and look at the back of the engine and the crank flange. The newer design has an aluminum seal body that bolts to the back of the engine. The crank flange is round. The old style has a counterweighted crank flange.