6 cyl Overdrive transmission

[69gmc292]

I was just see if anyone has ever but a 700r4 or a 200r4 overdrive transmission behind a 250 or a 292. I drive my truck everyday and it would be nice to take the freeway sometimes without my trucks engine sounding like it is gone to come apart. I have though about a manual swap but i kinda like my truck as an auto

[Wrenchbender Ret]

It will be an easy swap if you already have an automatic in it. The hardest part is hooking the throttle cable up to the 6 cyl. carb.

[72BlckButy]

Originally Posted by Wrenchbender Ret

It will be an easy swap if you already have an automatic in it. The hardest part is hooking the throttle cable up to the 6 cyl. carb.

Will it use the tranny member already there or will you have to pull the cross member and move it?

Same bell housing?

[N2GMTrux]

A 250 or 292 work best between 2000-3000 RPM range and depending on your gear ratio in your diff and tire size the fourth gear in the 700r4 or the 2004r would be to low (.70) I think... And would cause your engine idle down into the 1600 to 1900 rpm range in the fourth gear. Again you would have to figure your tire size and gear ratio to put you in the 2000-3000 rpm range.

[cris well]

i thought the 292's had a different bolt pattern at the engine/bell housing than a 250 or SBC-BBC.

i may be wrong.

['68OrangeSunshine]

Originally Posted by cris well

i thought the 292's had a different bolt pattern at the engine/bell housing than a 250 or SBC-BBC.

i may be wrong.

You are wrong, Sir.

[292farmer]

if i remember a member on this site said the gear ratio split on the 200-r4 works better then the 700r4 with inline 6's not as big a ratio diff, between 1st-2nd. just thought i'd add that for consideration.

[jablack]

Does someone make a carb bracket for the detent cable?

[raycow]

I haven't seen an aftermarket bracket for the 6, but you can adapt the stock bracket used for the TH350 cable.

Ray

[PanelDeland]

You will also have to check Driveshaft length,crossmember placement(or get one if yours is manual now)and steering column or shifter will need to be adressed.You will also have to remove the existing crossmember if yours is manual.

[69_hafton]

Just to give you a ballpark number to look for, I'm under the impression from past info gathering that a 3.73 gearing set-up is what you're looking for in the diff. I've got a 4.10 and can comfortably go 65 with the overdrive (I think it's a .73?), but much more than that and the rpm's get uncomfortable.

There are probably other ratios that can be used, but they aren't as common, but maybe for more top end you could find around a 3.54?

[Jacfourteen]

I thought most of the I6's were geared low (4.10-4.56, or is that with the Manual?) so they should still have decent highway rpms even with OD. Anyways the rear gear is def an important consideration. I've heard that you can find OD trannies with the same overall length so the driveshaft won't have to be modified. I think you can use the same crossmember, but you have to move it back a few inches and redrill the mounting holes in the frame. Other than that it will be a pretty easy swap.

[72gmcer]

I was planning on putting a 700r4 behind my 250 also. Converting from a manual three speed. Does anyone know of a build thread that touches alittle more on the subject with maybe some pics. I'm new to the site and just want to say that this is the most informative site I've ever visited.
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[jhyder408]

ist an old thread but I'm looking doing this... anymore input would be great. not necessarily concerned with gears but overall setup, manual to 700r4 in short box with a 250 6cyl

[Jurassic-1]

I was going to do the same thing on my 1966 truck. I have a 200r4 and asked Bowtie overdrives about the detent. He said there is not enough call for it and because the linkage is backwards it is more difficult to do. It can be done but the geometry should be on to not damage the transmission. I would also be interested if any one has install tips.

[arkansas]

I'm in the process of putting a 2004r behind a 250 in my 71. It originally had a factory T350 behind the 250 (odd combo but it's on the original spid). The 200 is the same length as a t350 so the driveshaft length is fine. The bell housing to mount location matches a t400 so you only have to move the stock crossmember to the t400 bolt holes in the frame so no drilling. Mine is all bolted in now but I've not tackled the cable yet. Still saving for FI for it first. The inlines were pretty torquey at low revs so I'm not too concerned about 3.73 being too high rear. Just pull it out if OD in town. I do that now in a Chevy coupe I'm running a 700r4 in behind a small block with 3.73 rear.