Volvo Repair: Key on only to make engine run., electrical portion, s 240

Question
Hi, I just swapped engines on same 1983 Volvo Turbo's (240 DL)2.1 engines. The old vehicle was an automatic and the new vehicle was a manual. The swap was easy but I have one persistent problem. The engine will only run as long as I hold the ignition key in the start position. As soon as I let go the engine dies. Lights come back on the dash. The engine ran fine with no problems in the other vehicle. I've checked for missed hoses or electrical connections but can't  find any. I swapped all available relays, ignition modules, and cold start modules from the old car with no success. Any ideas why the engine looses spark when the key goes back to the on position?

Answer
Tony, this is a pretty good one even for me who knows the old cars like the back of my hand.  There is no logical explaination for it.  Shouldnt matter if it was automatic of manual.  The harness should be the same.  Obviously there is something missing.  I know its a long shot but did you check the electrical portion of the ignition switch to see if it was the same?  Roger