Ok, I've found a good M46 to replace my failed M45 transmission in my 1980 242DL. As my car did not originally have the M46, there is no wiring in the car for the overdrive. The M46 I have came from either an '84 or '85 245, and the 4th gear lockout switch for the OD unit only has a single conductor pin in the middle of it. My question is, did the 1980 cars with the M46 have a different lockout switch with 2 conductor pins in it? The wiring diagram for the 1980 doesn't show a relay for the OD.

I've checked on IPD's site, and they show the OD relay and list it for '81 and up. Also, the switch that goes in the gear shift knob is also different for the pre-'81 cars and for the '81 and up. However the only 4th gear lockout switch they list is also for 1981 and up. Is there a source for the pre-'81 4th gear lockout switch? Can I just substitute a backup light switch in it's place since it has 2 conductor pins? I'm at the point where I'm just about ready to install the M46 but I want to make sure that I get the 4th gear switch and wiring all sorted out before I put the transmission in as it's impossible to access the switch once the gearbox is in the car. Any insight is greatly appreciated.

Billy McCaskill
242DL/GT with some IPD goodies