Piecing together an A/C system

A few years ago I had to replace the heater cores in both of my Dakotas within a few months of each other. You know the old, "replace everything while you're in there" thing.....
Well I didn't care about the AC on the 92 as the compressor was shot anyway.... It was basically an idler for the serpentine belt was all by now.
So I didn't worry about the evaporator on the 92.

When it came time to do the heater core on the 96 well it was in nicer shape overall and alot less miles at the time, so yeah I figured I'd do the evaporator on this one. What a mistake. On this one they showed 2 choices of evaporator. A parallel and a serpentine type.
I tried to research the difference (I was ordering part and didn't have it apart yet) to see what kind it had in there already (remember I couldn't see thru the firewall haha) and didn't know the difference.
I don't remember the price difference at the time but I believe the serpentine was more expensive.
So I googled all over to see what the difference might be, somehow I decided to try the serpentine one. What a mistake. It didn't fit the plenum right, to begin with. Had to cobble to keep it from dangling around. Then I couldn't get the drier to attach no matter what I tried. The 96 had the round style with the garter spring that takes the "disconnect tool" to release. The 92 which was still originally an r12 system, had flat flanges with shim-thickness metal gaskets. The 96 was r134 from the start. I never did get to charge the ac in that one and I wasn't taking the dash apart to re replace the evaporator, and wasn't about to pull the dash apart to redo the evaporator. So it's stayed un charged ever since.
That truck has seen better days, body is quickly falling apart, paint has peeled long ago, has 1/4 million miles on it, and has been basically demoted to my "mowing truck" in the warm months and my winter "beater with a heater" because of its 4wd and my 70 mile a day commute.