Currently the range of aftermarket products and services is very limited.  Below is a list of suppliers and parts i have collected from the Internet.   These are generally private individuals who have developed parts for their own use and have made some additional parts for sale. Vortec 4200  Parts available from Jerry Weight Jerry was able to get his hands on a genuine GM 4200 flywheel.  Only a few were made.   He was able to draw it up and have duplicates made.  Jerry is also making Intake and exhaust flanges, a bolt on rear sump and an extended oil pickup.    Contact Jerry directly at   “weights(at) sbcglobal.net)  change the (at) to an @ sign when you send the email Intake flange Bolt on rear sump Extended oil pickup Front view of 4200 Flywheel Front view of 4200 Flywheel