Not without major modifications.
the Serpentine Belt on the 91 Lebaron is on Tension Pulley, you dont tighten it. But if it is loose and you need to tighten it you just go and buy a new belt and put that on.
4.5 quarts
Yes, they are equal from 1987 up to 1995
Yes
No. They are not interchangeable.
Yes
Yes but you might have to get the bcm off the car you are taking the dash out of. I have a 91 Lebaron convertible that came from factory with the digital dash.
Yes it will.
35L
Yes it should fit the frame not sure if tank will fit as the 91 barrel and head are bigger
A 4L60E would not fit on a 91 Silverado because of the different dimensions.
YES IT WILL FIT