Auto Transmission Problems

Hi All!
This is the first time I've worked on a BMW but far from the first time I've had problems with a car. A friend asked me to try and get his sisters 1991 E30 318I 2door with a 4hp-22 gearbox, going again for her. So I thought that I'd give it a go. The problem that took the car off the road was that the automatic transmission blew up as he told me. There was reverse gear but no forward gears.
So he went out and brought a second hand gearbox (also has 4hp-22 makings) supposedly from a running 318i. year unknown. I came along a dropped out the old gearbox and went to install the new one.
This is when the problems started.
Firstly the bell housings were different. So I swapped the old housing onto the new box and that went ok.
Secondly on closer inspection I noticed that the old gearbox had an inhibitor switch near the gear selector lever (At least thats what I think it is) A small electrical 2 pin connnector. The new gearbox didn't have this.
Thirdly I noticed that on the intermediate plate (the bit behind the bell housing) Where the oil cooler lines screwed in were different the old gearbox had lines that screwed directly into the box, the new box had screw inserts with a Torx# 55 pattern on the inside (at least thats what I used to take them out.) The thread on the intermediate plate was smaller than the oil cooler hoses.
Fourth problem was that the new torque converter's flywheel mounting nuts were ever so slightly smaller/ closer to the center than the old torque converter. So i used the old torque converter on the new box which seemed ok.
Last but not least I've installed the new gearbox, got it tightened up to the engine, the gearbox cross member installed and the driveshaft connected to the gearbox. The rear driveshaft hanger bolted up and now the driveshaft seems about an inch too short.

Chapter 2. (I didn't think this was going to be a short post Thanks for your patience.)

Can anyone help me identify why there are differences in these gearboxes, namely the bell housing and the oil cooler lines and inhibitor switch. and does this make a difference in the overall length of the gearbox. I'm open to suggestions such as different years maybe 318 vs 325 2door vs 4 door, different prop shaft lengths or do I just need to apply some force to make the driveshaft meet the diff?
Do I need the inhibitor switch? Im guessing that the electronics in the car that donated the new gearbox are different, Is there something I can get and put into the car that I'm working on so that I don't need the switch?
If there is a difference in the overall gearbox length is there a longer propshaft or longer propshaft-driveshaft coupler available?
Does anyone know of a threaded coupler without the internal torx design that i could screw into the intermediate plate to connect my existing oil cooler lines?
Is Anyone able to provide a detailed service manual for An E30 with the gearbox section in it? I've found a couple online but they don't have the info I need.
And though I hate to admit it in the words of mythbusters "Failure is always an option" do I just need the right gearbox? If so, are you willing to ship 1/2 pound of C4 for a youtube video of a gearbox being blown up? "When in doubt C4!"
Thanks for any and all of your ideas.

sounds like he grabbed a early model tranny and you need the newer version. even though they have the same model numbers, they do upgrade them throughout the years.