1950s 1956 Eldorado engine and transmission question

[CRAIG LEWIS]

I just aquired a 56 Eldo engine and transmission. The engine is complete and on a stand I have not delved into it yet but looks to be in good condition. Still has the original choke heat riser to teed to both carbs with the cloth insulation on it. My question is the transimission that came with it is a  56CE  and looks untouched as well. How can I tell if it was upgraded at all to address the 56 issues. It still uses the 4 sprang attachment to the flex plate on the fluid drive. Is it worth dealing with it or will a later Jetaway such as 59-63 bolt to the 365 without an adaptor? I sm in Phoenix anyone know a reliable shop that knows the 56 transmission?

I have a 51 62 series and I plan to drop the 365 and Jetaway in it.

[Roger Zimmermann]

The rear extention is specific to 1956. Other years have a shorter tail extension. To use a more recent transmission would require the replacement of the extension and drive shaft. To do the exchange, the drive shaft/drums/clutches must be removed from the transmission's front. Quite a job!

[CRAIG LEWIS]

I read that the tail extension was the only real issue with going to a 57 is it the same with say a 63 does the 390 bold pattern match the 365?   Anyone know the decode on my engine number doesnt match up with Cadillac but the serial number on the front passenger head area is for a 56 series 62. The rear driver side stamp shows 4XK797. Casting number is 1483378 or 1463378 cant tell.

Thanks

[Roger Zimmermann]

4XK is a '56 engine for cars with A/C, but without dual carbs.
The bolt pattern is identical for both engine types.