i need an opinion on which gear ratio to run 3:73 or 4:10. Motor is a 383 SBC roundabout 400 hp and im running a Th-350 trans. It will not be an everyday driven vehicle. Probably like once a week or so. and an occasional trip down the quarter mile. being that the trans is only a 3 speed im not sure if the 4:10 will be too low to drive on the street but then i want the car to take off good so i dont know if the 3:73 will be too high. Also what is a good posi unit to run? Thanks

 

I've run a th-350 for about 10 years now, but am now in the process of changing over to 700R4 since changing the rear gears to 3.73's. With those gears on the highway I was turning to many rpm's for my liking. I don't know that I would go to 4.10's unless I was running overdrive. A friend of mine who does run 4.10's says it too much for the street without overdrive. He says he wants to drop back to 3.73 or even 3.42's. I had the 3.42's but really like the 3'73's. Good luck in your choice.

 

How many RPM's were you turning on the highway with the 3;73's

 

At 60 mph I would be running around 3000-3200 rpm give or take. When I started going to further shows and was running 65-70 mph on the freeway I would be close to 3800-4000. Probably didn't help that I have a short tir combo either which adds to the rpm's.

 

This is my only regret about going from a T5 to a T10 4-speed. Meh.. I'll get over it

 

Being a 383ci. on the street, I would stick with 3.73's and a Continental 10" with the TH350 transmission. A good 7.5" posi is the Eaton. Call me if you need one?