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Ok so ive blew my TH 350 transmission twice after swaping out my stock 8.2 rear to my now 8.5 10 bolt 3.73 posi rear. I understand that with the new rear my engine ran alot hotter and in higher Rpms. this has taken its toll on the trans. now im sure if i go the 700 r4 route ill have the extra gear so i wont hav to be driving like 55 on the freeway! what issues will i face drive shaft clearance?
cross member mods? if so what exactly?

71 nova
350sb
th350
8.5 3.73 posi
 

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I am very interested in this swap as well, mine will be from a PG to 200r4 or 700r4, not sure yet. I don't know all the answers to your questions but you can surely find them on here. I have had these same questions and they have been asked many times over on here and can be found by using the search function. Good luck with the swap!

Kirk
 

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I am interested in the same swap! And I'm not trying to NOT help you, but do a search on 700R4 ... you will get 19,726 previous posts on this subject. :yes:
Wow! 19726 posts. That is a lot of info.

Also, ultimega, go to www.bowtieoverdrives.com From what I have found in my search on this site they have will gladly answer questions and have all the parts you will need as well as great customer service!

Kirk
 

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Here is something I copies from Wikipedia:

Quote: [edit] 200-4R
In 1980, for 1981 models, GM's Hydramatic division decided to incorporate an overdrive gear, and using the THM200 as a base, the Hydramatic 200-4R was born. Internally, the components which were prone to failure in the THM200 were improved, and this transmission was used with high-power applications - primarily the Buick Grand National. GMs powered with the Oldsmobile 5.7L Diesel powerplant were coupled with the 200-4R in place of the 200.

Unlike the 700R4, the 200-4R has a multicase bellhousing for use with Chevrolet and Buick/Olds/Pontiac/Cadillac (BOP) powerplants. Since the external dimensions are similar to the THM-350, 200-4Rs are usually swapped in place of THM-350s in older vehicles to provide an overdrive gear.

Early models had PRND321 on the cluster, while later models had PRNDD21, with the left D identified as the overdrive gear by a square or oval ring.

The THM200-4R was phased out after 1990 - its final usage was in the GM B-body lineup (Chevrolet Caprice, Oldsmobile Custom Cruiser station wagon, Cadillac Brougham) coupled to either a Chevrolet 305 or an Oldsmobile 307 engine. It is believed that an HD version of the 200-4R was used in the late 80s Caprice 9C1 police package using the internals from the Buick Grand National

Unquote

I am using the 200-4R from a 85 Buick LeSabre in my Chevy. I understand from other searches that 1986 and up are better donors.
 

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Ok so ive blew my TH 350 transmission twice after swaping out my stock 8.2 rear to my now 8.5 10 bolt 3.73 posi rear. I understand that with the new rear my engine ran alot hotter and in higher Rpms. this has taken its toll on the trans. now im sure if i go the 700 r4 route ill have the extra gear so i wont hav to be driving like 55 on the freeway! what issues will i face drive shaft clearance?
cross member mods? if so what exactly?

71 nova
350sb
th350
8.5 3.73 posi
I ran a 700R4 in my p/u truck for a while. for that it was a real easy swap, idk if it would be just as easy in a nova.

this is what it consisted of; shortening the drive shaft (i think 3in) and unbolting the cross member and moving it back (i think 1.5in) I can't remember all the numbers exactly. but you will definitely need an auxiliary trans cooler, and you MUST have some form of lockup set up for the torque converter. a 700R4 cannot use a non-locking torque converter, if the torque converter doesn't lock then 3rd gear doesn't disengage for fourth and burns out your clutches and hurts gas mileage etc... tv (throttle valve) cable is required also. other than that, it bolts right up, the shift linkage fits right up. (i'd recommend buying a stronger one though, in stock form the 700R4 can only handle like 270 horsepower or something thats what they say, mine was behinds a 290 horsepower crate engine and did just fine with a mild truck rebuild/shift kit) good luck
 
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