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th350 with unknown plug switch...????

17K views 4 replies 4 participants last post by  fast68 
#1 ·
hello everyone,
i just recently bought a used th350 tranny a couple days ago. Its the th350 with the long 12 inch tailshaft housing. the guy who sold it to me said its kinda of a rare one having to 12 inch tailshaft. Anywase i was checking it out and i noticed on the passenger side of the case next to the kick-down cable was an electrical plug with two prongs on it. Its circle shape and the surface of it looks like its porclain. well, i did some reearch online and came up with a bunch of info about the th350c trans.(lock-up kind) which i was hoping mine wasn't... ;) After researching i'm convinced its NOT the lock-up converter type; cuz of an electrical plug being on the drivers side by the shifter link and also it having a 4 prong squarish plug. The only thing i found about my tranny is a guy on a forum said the early th350's (guessing 69-71) have some kind of spark control or nuetral plug switch on them...i don't know. So can anyone tell me what this plug is for and will it hurt anything not being hooked-up?

thank you much,
Mark
 
#2 · (Edited)
The 12" tail is kinda rare- just makes it more of a b**** to find a driveshaft for it. IIRC, '77-'79 or so wagons used the 12" tailshaft TH350.

To tell if a tranny is a lock-up TH350C, check the input shaft. The TH350C has a polished end on the input shaft and there will be a rubber O - ring too. It will also have a TCC connector. The TCC lock up connector can be 2 or 4 prong, and is located near the shift linkage, on the drivers side.

The TH250C will have a threaded stud/lock nut (band adjustment) near the cooler fittings, passenger side, along w/a TCC connector.

will it hurt anything not being hooked-up?
Not if it is a TH350, no lock-up TC.

The tranny spark control switch is located on the passenger side, has one wire and screws into the case. It can be left in place, or removed and the hole plugged w/a threaded plug.

Bottom line: What you've described is a 12" tailshaft, TH350 W/O TCC lock-up TC.

It does have the switch for tranny spark control- it will not hurt the tranny to run it w/o it hooked up.
 
#3 ·
350 lock up transmissions never came with a 12" tail from the factory. 250 transmissions never did either. So, unless someone has changed the shaft and tail (extremely unlikely), you have a Non-lockup 350.

Lots of 250/350 transmissions came with a switch screwed into the tap near the TV cable. If you don't need the switch, leave it unhooked or replace it with a pipe plug.
 
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