Manual Tranny ID

e_man · November 12, 2006

I have a 1989 GMC C1500 w/305 w/5spd. The tranny is starting to wear and I wanted to know exactly what transmission I have so I can order parts or buy a whole new one. From my research on ther sites and from what other people have told me I have a couple of options. I can either have a Getrag HM290, Muncie 5LM60, or a New Venture 3500. Now I have found my RPO code for my transmission and it is MG5. But that doesn't really tell me anything. When I search for that code it still brings up all three. Now I have read but not sure if it is correct but the NV 3500 is for 90-up and the other are for 88-90. But the problem for the 88-90 I read is there are a couple of different versions an early and a late. So I have no clue as to what I have.

Now my second question is about changing transmissions. I have heard the one I have is weak and is known to have problems and to change to a New Venture 4500 from an early 90's model I belieave 3/4ton truck. Due to its strenght and cast iron case. But is it a direct replacment for my old tranny(whatever it may be)? If I have to change my driveshaft due to different length that is fine. My main concern it will the sensors either from the NV4500 work with my wiring harness and computer or will my old sensor plug into the new tranny. So the backup lights and speedometer will still work correctly. If you could help I would appreciate it. Also just to clear things up, from reading the rules for this section this is all GM parts not aftermarket transmission I am wanting upgrade to.

GM-Tech · November 12, 2006

Also just to clear things up, from reading the rules for this section this is all GM parts not aftermarket transmission I am wanting upgrade to.

<{POST_SNAPBACK}>

Understood, but you're still asking about modifying something from stock with which I have no experience. Will it fit? I have no idea. Are the wiring connectors the same? I have no idea, etc., etc. Put in what came out and you'll be okay. Otherwise, you're pretty much on your own unless you're lucky enough to find someone here who's done the exact same thing.

I don't know exactly what a MG5 is, but your local dealer's parts dept. should be able to tell you what you have if you bring them your VIN.