OK, Here is the deal. I have a 350 hp big block with a power glide (which needs repair)and a 373 ls rear. Do I:
1) Rebuild the powerglide and rebuild the 373 to posi.
2) Install a new Turbo 400 and change out the rear to a 12 bolt 342?
3) Install a new 700r4 and go with the 12 bolt?

I enjoy cruising, but would like to be able to hold my own, just in case. Any suggestions? [sm=helpout.gif]

 

Maybe I don't understand the question? I'm not sure what motor you have, butI see no reason that you couldn't run the 3.73 gears with any tranny that you choose ( the 400 turbo for strength, the 700R4 for better mileage)! I have several B.blocks, & they will 'keep up' with two plug wires laying in the trunk!
If all that you are worried about is the posi (limited-slip) carrier, then put a posi-unit in your rear-end. If you are running a 10-bolt & are worried about it holding 350 horses, DON"T! I have been flogging my Zexel torsen with 450+ hp for about 60K, now, & it's still there (with 3.42 Richmond gears BTW)!
Also, if you do choose to run the 400TH, remember that you will be taching-up about 2900 rpm (with 1:1 drive &26" tires) w/ 3.73s at 60 mph. The same combo w/ 3.42s will still be taching about 2650 rpms.
So, if it's the mileage that you are worried about, then you should go with an OD tranny. Check this site, I don't know their prices or rep, but maybe they can answer your questions:
http://www.700r4.com/sitemap.shtml
John

 

Thanks for the reply. (I have a 396 and 24" tires)I guess I'm ready to pull the trigger to spend the cash and want to make sure I'm going to get the most bang for my buck. I'm not worried about the highway milage as much as I am concerned that I will be adding performace and value to the car without breaking the bank. I don't want to look back and say I should have or I could have.
I had a mechanic tell me that I would be pulling 2300 rpm's with a400 TH and 308 gears @ 60 mph[&:]?
What would you do if it were your car?

 

[X(] dejavu this is the second time here in recent weeks this exact same question and combo of parts has appeared. and ill give you the same advise, the 700r4 will provide the best overall situation for you as it has an extra low first gear so you dont necessarily have to go with 373 or 411 rear gears to get a quick launch, but it also has the true overdrive so the engine wont have to scream to get down the freeway. probably the best gears for the rear with this trans would be in the 308-373 range and the 10 or 12 bolt can handle the hp numbers your talking about. as for the rpms at 60 mph it sounds pretty close as thats about what my 454 nova with 308's would run on the freeway, might be a little high but should be close kurt