1985 Cadillac Fleetwood - Parts always seem a bit off

I bought a used 1985 Fleetwood 6 years ago and ive usually done the small repairs myself. I always seemed to have trouble with parts not quite fitting right. I dont do electrical work and asked afriend to help. One of the relay switches needed replaced and he figures out that my fleetwood has an Eldorado engine that appears to be factory install. Is that possible? How do i find out more?

Well first off. What model Fleetwood do you own? The front wheel drive (FWD) Fleetwood or the Fleetwood Brougham rear wheel drive car (RWD)?

The FWD car has a Cadillac-only engine. Both the E-body Eldo and the C-body Fleetwood used the 4.1 liter pushrod engine in '85. 135 hp, weak-kneed V8 engine. Same engine was used for '85 in the RWD D-body Brougham models. The RWD version changed to a 307 Oldsmobile engine in '86.

All on Wikipedia, BTW.