Wanted trans info - The 1947 - Present Chevrolet & GMC Truck Message Board Network

23and56 · 06-12-2002, 08:49 PM

Have 85 1/2 ton which trans quit today and I have two 700r4s from 3/4 ton vans 90 and 91.Shall I stick with 350 turbo or go to 700r4. Truck is going forsale whatever way I go.Also have 350 trans from 78 van but it dosen,t have the 3 prong plug 85 trans has.Any ideas thanks

batboy · 06-13-2002, 01:44 PM

If you want to do minimal work and parts chasing, then in my humble opinion, replace it with another 700R4. The 350 turbo is shorter, so you'll have to find a longer driveshaft, relocate the cross member, and mess with other stuff like that.

1974ChevyC10 · 06-13-2002, 02:52 PM

does your truck have a TH350 right now or a 700R4?if it has a TH350 then imo you should stick with that.i know i would catch some h*** for saying this but i dont like 700R4's and for the cost involved in having a TH350 truck converted over to a 700R4 you could build 3 or 4 TH350's and for the cost of swapping you only gain about 2 MPG-a friend of mine back home had his 77 K5 swapped from a TH350 to a 700R4-cost him 1500 dollars in total and he went from 10 to 13 MPG's-not worth it imo for a 3 MPG gain.so basically i would stick with the TH350 and since your selling it anyway then with the TH350 you would have less cost involved in a truck your not keeping.the 3 prong plug you mentioned is just a switch for a lockup convertor(TH350C) and if you do go with the 78 tranny it will still work you just wont have the lockup ive ran them both ways to me there not that big of a deal but some people like them.just my 10 cents on the subject

batboy · 06-13-2002, 05:09 PM

Yes, good point. Guess I assumed it had the 700R4, since that's what it should of had originally. If it has a 350 in it right now, by all means, stay with the 350.

23and56 · 06-13-2002, 11:11 PM

My glovebox door says trans is mx1 3spd.Does anyone know of trans decoding site.Did 85s offer 350 and700r4s trans?Thanks

1974ChevyC10 · 06-14-2002, 05:03 AM

i do believe in 1985 they offered both the TH350 and the 700R4.

gchemist · 06-14-2002, 08:56 AM

700R4 started in '82 in limited amounts. '83 and later models were more popular with the 700R4. If you have R-N-D-2-1 on the column you have a 350TH. If you have R-N-D-3-2-1 then it's a 700R4. Both were availble for our trucks. Stick with a stock replacement since you're selling it. If your keeping it install the 700R4. I have a 700R4 in my truck. It's not stock either.

Sure it cost me $1100 bucks but I would put it up against a stout 350TH any day. Put a truck with the same engine same drive train and I'll choose the 700R4. That first gear is a real killa. The 90 and 91 700R4s were the best ever made. By that time all the weak spots were mostly fixed. Those models could even run without a locking torque converter. Only 82-84s require lockup or they will burn up.

350th pan - square with a corner cut off. Modulator pointing to the rear of the truck.
700R4 square oil pan and no modulator. It does have a four prong connection on the driverside.

06-12-2002, 08:49 PM	#1
23and56 Registered User Join Date: Jun 2001 Location: barnum Posts: 127	Wanted trans info Have 85 1/2 ton which trans quit today and I have two 700r4s from 3/4 ton vans 90 and 91.Shall I stick with 350 turbo or go to 700r4. Truck is going forsale whatever way I go.Also have 350 trans from 78 van but it dosen,t have the 3 prong plug 85 trans has.Any ideas thanks

06-13-2002, 02:52 PM	#3
1974ChevyC10 Overworked and Underlaid Join Date: May 2002 Location: Flagstaff,Arizona Posts: 1,279	does your truck have a TH350 right now or a 700R4?if it has a TH350 then imo you should stick with that.i know i would catch some h*** for saying this but i dont like 700R4's and for the cost involved in having a TH350 truck converted over to a 700R4 you could build 3 or 4 TH350's and for the cost of swapping you only gain about 2 MPG-a friend of mine back home had his 77 K5 swapped from a TH350 to a 700R4-cost him 1500 dollars in total and he went from 10 to 13 MPG's-not worth it imo for a 3 MPG gain.so basically i would stick with the TH350 and since your selling it anyway then with the TH350 you would have less cost involved in a truck your not keeping.the 3 prong plug you mentioned is just a switch for a lockup convertor(TH350C) and if you do go with the 78 tranny it will still work you just wont have the lockup ive ran them both ways to me there not that big of a deal but some people like them.just my 10 cents on the subject __________________ I'd rather push a Chevy than drive a Ford The Beast-1978 C10 LWB Red-1978 C10 LWB (Uncle Mike)Michael Henry Millett 11/5/1957 to 03/08/2012 Gone but will never be forgotten-RIP (Uncle Chuck)Charles Manning Gulbronsen Sr 1956-2012 Taken from us to soon but you will live on in our hearts-RIP

06-14-2002, 05:03 AM	#6
1974ChevyC10 Overworked and Underlaid Join Date: May 2002 Location: Flagstaff,Arizona Posts: 1,279	i do believe in 1985 they offered both the TH350 and the 700R4. __________________ I'd rather push a Chevy than drive a Ford The Beast-1978 C10 LWB Red-1978 C10 LWB (Uncle Mike)Michael Henry Millett 11/5/1957 to 03/08/2012 Gone but will never be forgotten-RIP (Uncle Chuck)Charles Manning Gulbronsen Sr 1956-2012 Taken from us to soon but you will live on in our hearts-RIP

06-14-2002, 08:56 AM	#7
gchemist BAD BOW-Silverado XST Join Date: May 2000 Location: Senior Member from Austin, TX Posts: 6,431	700R4 started in '82 in limited amounts. '83 and later models were more popular with the 700R4. If you have R-N-D-2-1 on the column you have a 350TH. If you have R-N-D-3-2-1 then it's a 700R4. Both were availble for our trucks. Stick with a stock replacement since you're selling it. If your keeping it install the 700R4. I have a 700R4 in my truck. It's not stock either. Sure it cost me $1100 bucks but I would put it up against a stout 350TH any day. Put a truck with the same engine same drive train and I'll choose the 700R4. That first gear is a real killa. The 90 and 91 700R4s were the best ever made. By that time all the weak spots were mostly fixed. Those models could even run without a locking torque converter. Only 82-84s require lockup or they will burn up. 350th pan - square with a corner cut off. Modulator pointing to the rear of the truck. 700R4 square oil pan and no modulator. It does have a four prong connection on the driverside. __________________ Gerardo a.k.a. Mad Chemist Silverado XST videos

06-13-2002, 01:44 PM	#2
batboy Registered User Join Date: Mar 2000 Location: Kansas, USA Posts: 175	If you want to do minimal work and parts chasing, then in my humble opinion, replace it with another 700R4. The 350 turbo is shorter, so you'll have to find a longer driveshaft, relocate the cross member, and mess with other stuff like that.

06-13-2002, 05:09 PM	#4
batboy Registered User Join Date: Mar 2000 Location: Kansas, USA Posts: 175	Yes, good point. Guess I assumed it had the 700R4, since that's what it should of had originally. If it has a 350 in it right now, by all means, stay with the 350.

06-13-2002, 11:11 PM	#5
23and56 Registered User Join Date: Jun 2001 Location: barnum Posts: 127	My glovebox door says trans is mx1 3spd.Does anyone know of trans decoding site.Did 85s offer 350 and700r4s trans?Thanks



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