This thread is for detailing the install of a 42RH or A-500 in an A-Body. This should also apply to either an A-518 or 46RH as well since they have the same overdrive unit as a 42RH. The car in question is a 1974 Duster with a late model 1994 5.9 with Enginequest heads, CompCams .510 roller & Edelbrock RPM intake. The car currently has 318 manifolds which are going in the trash since I had to cut off the front section of the dual exhaust and H-pipe anyways. The manifolds will be replaced with a '73 340 manifold on the drivers side and a early magnum Dakota manifold on the passenger side with 2.5 inch outlet. The purpose of the 42RH swap is to improve the launch of the car (2.74 first gear vs 2.45 in the 904 and better converter,) improved mpg (1900 rpm at cruise vs 3500 rpm,) higher top speed and less cabin noise at speed due to the lower operating rpm. The 42RH is pretty much just a slightly newer version of the A-500 from a local yard (1994 Dakota 3.9 application in this case) It had a 4/4 clutch setup which will be updated to a 5 clutch setup with either a different drum or thinner steels. Pictures and more details will proceed this post! Gary PS: Please do not inquire in this thread about weakness or strengths of the 42RH / A-500, transmission upgrades or how it will be shifted into overdrive and lockup. The narrow focus of this thread is how to install one in a car, period. Trans upgrades and shifting of the overdrive unit and lockup will be covered in their own threads and I'll request moderators to remove any non thread related posts so things remain concise and to the point for your reading pleasure Thanks!