I now have my self a 68 RS . It now has a 10 bolt with a highway gear 327motor T350 trans.
Long term new 383 motor and 700r tranny.
Short term New rear end. This is not a drag car It will be my weekend hotrod.??? what gear should I get 3.55 or 3.73
Will the 10 bolt be OK with new gears and axles (street tires only)
I think the 3.73 would be nice with the 700R but with the t-350 the 3.55 would be better?
It will be a year or so before I can get the 383 / 700r setup.
What do you think. (do not want to have to do this twice. and do not do a lot of highway driving)

 

3.42

 

3.55 I liked my 3.73, but it was hard to get going w/o spinning the tires with stock tires and suspension

 

3.73 with 700r4 the best out ther

 

3.73

 

what size tires are you guys going with on your 1st generation
Will a built 10 bolt hold up with street tires. (no drag strip)

 

To convert to 700 you would need to shorten driveshaft, move trans crossmember and address the lock up torque converter, some of the 700s have a different output spline also. A friend of mine put a 700 in his 79 Z which was mostly a strip car, the drop from first to second wouldreally dropthe rpm of the engine. I had a th400 I gave him and he had rebuilt it was a huge improvement at the strip. In general the only advantage of the 700 is the overdrive. I doubt you would see a big difference between the 3.73 to the 3.55 ratios it would depend on the power curve rpm of the engine/ tire size, given its a 383 I would lean towards the 3.55:1 though.

As I think you might have already heard the 1st gen 10 bolt is regarded as a weaker rear end, the 2nd gen 8.5 10 bolt is stronger as is the 12 bolt and the ford 9 inch. Will your 10 bolt hold up for street crusing just for driving around I would say yes. If you plan on putting alot of stress on it with a high torque engine, posi and higher gears running it hard I would say you are in the danger zone. 12 bolts and the ford 9" can be expensive the 2nd gen 8.5" 10 bolt are of a different dimention the easiest way to go might be to find a late 70s (you want to check the years on this) nova/ventura 10 bolt 8.5 inch I believe they are the same dimention as yours and mightbe more worth while to sink your money into.

 

I had a 71 with a 10 bolt 3.07 0r 3.08 rear gear....factory posi with a 350 4 speed drove it for 3 years then changed to a hard shifting turbo 350. did a cam change and i drove the hell out of it for2 moreyears, had no problems.comething like 50,000 miles.built a 427, nash 5 speedand changed to a 9 inch. sold the engine/tranny and rear to a guy with a 78 and he's still using it....My suggestion is that if it ain't borke, change the fluid to synthetic and drive the hell out of it...

Greg

 

GRIFF
Thanks I think I will order a 12 bolt from DTS or srange this spring. It will be a year or two before the 383 stroker and new trans.($$$) I will have to see what rpm at 60 eash gear will do on a 26.1 tire and t350 trans.