i have an 87 opera coupe 4.1L with a burnt valve and the tranny going out.now i can geta 90 sedan deville with a good 4.5L and good tranny for $450.what i want to know is if the 4.1 and 4.5 is interchangable both motors are tbi.i,m new to the site and trying fix gramps caddy.

It will bolt in,every thing will plug in,but there are normally drivibility concerns. Ecm's stock calibration doesn't work well with swap. There maybe custom PROMs out there to solve drivibility.Hope it helps