58roadmaster

If you are just looking to bolt the 54 Hydramatic to the 60 Olds 394 the process is relatively simple as I have done one. First you must have a "R" type dual range hydramatic (your's should start out like this: R54xxxxxx for the transmission model number). If this is correct then the next question is: do you want to mount the starter on the right? If so you will need the adapter you mentioned. But if you don't care that the starter is on the driver's side then the standard lower bell housing will work just fine. Now for a little information you will definitely need. There are three things I had to do to adapt a 60 371 to a 54 Hydramatic. They are as follows: 1) You will need to have the crankshaft flywheel end drilled out to accept a pilot bushing. 2) You will need to have the 54 Hydramatic flywheel "counterbalanced" to match the engine balancing. 3) If you are using the 1960 driveshaft you may have to have this (at least front driveshaft) balanced. Other notes: If you intend to use the 1960 starter (which is what I recommend) you will have to change the starter drive to go from course to fine tooth configuration. The locating dowels, which are on the Jetaway transmission will need to be installed on the engine block as the 54 Hydramatic has only the locating holes. The linkage from the 1960 will have to be bent a little to match up the throttle valve lever travel. After that you should feel a more distinct 2-3 shift from the previous dual coupling Jetaway slushbox. Good luck