700r4 Swap into a Blazer

[OlyHeeebz]

It's nice to see the search feature was put back on this site, however, searching under term "700r4" doesn't come back with many results.

I'm considering swapping out my TH350 for a 700r4 in my '69 Blazer. I've heard all the horror stories about thr 700r4 grenading under even moderate power and blah blah. But my engine (350) is not that beefy, and I don't hammer down when i drive. Just want it for cruising around town. It'll be getting mated to a NP205.

So what are is the list of donor vehicles that would be good candidates for a swap? I only know to search for tranny's made after 1987. Any other suggestions? I've been on the www.700r4.com website and seen their TV linkage kits, which I'll probably get.

What else needs to be done to get it to fit?
Shorten the driveshaft?
New crossmember?
What kind of adapters?

If anyone has done this swap before, any info is greatly appreciated. Thanks!

[qksilver]

I would gp with an 87 or later combo rather than an adapter, money wise. gn4u2c has a 700r and transfer case for a good price but he is on the east coast. You will need to shorten the rear and lengthen the front if you use your driveshafts. Go with the 87 later front driveshaft and I think the rear would work. Basically find a 87 or newer blazer donor and use everything, trans, transfer case, driveshafts, and cross members, it should be close to bolt in as far as all the dimentions.You will have to drill new holes for the cross member. Just make sure that your pinion and rear tailshaft angles are the same or very close. Otherwise major vibration problems will occur
Steve

[smokekiki]

If You go with the adapter,You can keep Your 205 and move the engine forward,I think it is 1.75".That way the drive shafts and transfer stay the same,and if You put a hei in,it will give You a lot more clerance to the firewall.That is the route I am going.My trans is being rebuilt,so I will have the shaft I need put in then.

[HatGuy]

It will be next year before I can do this but I
have been looking at these 700r4 transmisions.
http://www.bowtieoverdrives.com/cata...SUBCAT&CATID=B

[OlyHeeebz]

Yeah, I saw those bowtieoverdrive tranny's for sale. Look pretty good. There is a guy in Seattle with a tricked out one for $1,100 (on craigslist) too. However, I'm trying to do this on the cheap (well, relatively speaking), and want to pull one from a wrecker and have the local shop rebuild it.

Can I use an adapter for my np205 and keep the engine mounted where it currently stands? Or is there no other way around it if I want to keep the 205?

Also, aside from fullsize Blazer's made after 1987, would a 700r4 from a 1990 S-10 Blazer 4x4 work (it was mated to a 4.3 V-6)?

I don't think it's necessary to find a donor 700r4 specifically from a fullsize truck with V-8 engine, but I could be wrong???

[smokekiki]

The 700r4 is 1.75' longer than a th350.That is why the engine or transfer needs to move.

[FRENCHBLUE72]

I have been looking into this but have yet to be able to finance it btw didn't bobby-k do this swap???

[71RestoRod]

You pretty much have two routes you can go.. There's an Advanced Adapters rear output shaft that can be swapped in the transmission, but this requires a complete tear down. You can also get an adapter plate that goes in between the trans and transfer case... works with the stock output shaft but this adds even more to the overall length of the assembly. The advantage with the plate is that you get much better clearance at the front driveshaft. With the AA shaft, it's really close and I doubt you could ever get a deep tranny pan in there without major modification.

I used the AA shaft and (following BobbyK's advice) moved the engine forward 1 3/4". If I were to do it again, I might think about using the plate adapter instead and then moving both the engine forward and the cross member (transfer case) back. I think the engine is about as far forward as I would want to go at this point.

Sorry I can't find a link to the plate manufacturer.. it was in Texas. I think I remember it being referenced on this board though.

Also, you'll want to look for a 'K' -case 700R4... It's a beefier case used in trucks. If you look at the attached pic, you can see the 'K' on the side.

[72c5]

I have a 700 R4 in mine, it is a 4wd trans, works great, but the gap between 1st and 2nd gear is really big.........i'm seriously thinking of using thge 200-r4 trans when i swap to 2wd this winter...........the 200-r4 is the only GM 4-spd auto with a closer ratio between 1&2...........i'll probably just use a bone yard trans, but if you buy a reman trans, then it will probably be just as strong as a 700-R4...........

[OlyHeeebz]

72c5, to install your 700 then - which adapter did you use? Did you have to move your engine forward or T-case backwards? How did your rear drive line angles turn out?

Has anyone used those pre-made tube crossmembers that you can buy from bowtieoverdrives.com?

[Nightrider]

Much easier too go 3.42 and keep the 350 trans,with 33 inch tires. Works pretty good everywhere....

[nmaggie99]

What's the easiest way to move the engine forward 1.75??? The Blazers don't have two different sets of motor mounts like the 2wd pickups (I-6 vs V-8). Any pics or diagrams would be useful.

[61STEP]

I put a K-case 700 from a 94 s-10 in my 69 CST. I was told the S-10 trans has quicker shifting valve body. It also has the outer edges of the bell house trimmed so you can remove it without disconnecting your headers.
I left my 205 in its stock location, used an OEM 2" spacer on the back of the trans, and trimmed 3/4 of an inch off the output shaft. I didn't have to change drivelines and had enough clearance for a deep aluminum pan.
With the trans and t-case in place I bolted in a bigblock to the trans and used a 73' up crossmember. There was one original hole on each side of the frame that lined up and I drilled the rest. This moved the motor forward, but I have plenty of room behind the tall valvecovers and a 2" fan spacer in front. The 73' up crossmember uses stronger motor mounts and allowed a 8qt pan, that can be removed with out lifting the motor.
With 4.56's axel gears in a 14 bolt, 35" tires, 4" lift and 420 horse big block, it runs around 2200 rpm at 70mph in overdrive. Without a doubt the 700 swap is the best mod I have done to my blazer. Hope this helps.

[OlyHeeebz]

61step,

That sounds like a great setup you have there! I'd love to have something similar, although I don't think I need so many ponies.

I don't suppose you have any pics of the work you did in progress?? What 2" OEM spacer is that you used? Or is that something from Advance Adapters?

How hard was it to cut the output shaft 3/4" of an inch?

Also, this might be dumb question, but do you think a '73+ crossmember will work for a smallblock engine too? I'm don't know much about the motor mounts.

Also, I'd be running 3.73's in GM12bolts with 35" BFGs, but will likely downsize to 33" tires soon. I'm trying to figure out what rpm my engine might be at at freeway speeds....

Thanks!