Different cam cases between 85,86 and 87,88,89?

So are these different. I have been having some trouble ever since I got my 86 t-wagon. I cannot get the time the thing to 25 deg, the closest I can get is about 27 deg. Yes I have checked the belt timing and have even tried to restab the distributor.

Little history

Got the car for free, came with 2 heads that were supposably blown and some other misc parts some of which I cannot remember and might have been cam cases too for all I know.

Here is what I am thinking. Car blew a HG heads cracked, mechanic replaced heads and cam cases from a newer gen so when I put my 86 disty in the 87 and up cam case I am off a little.

Looking through my 85 FSM the drawing for the cam case looks a little different but I want to get a finally answer from someone who has actually seen the 85 86 cam cases.

Also I am aware of 87,88,89 cams being a little better preformace wize is the disty gear in the same position as the 85,86 cams. Is it a direct cam swap, no strings?

Thanks a bunch

Sorry to be so wordy

Mods if this is in the wrong forum feel free to move it. I figgured it was a little more indept and a little modish?