rear end help
 

okay guys i got it apart, i want to get the housing powdercoated this week and get it reassembled. what i have is a stock 12 bolt out of a 72 truck. what i am installing is a 5.3 motor with the transmission. i dont know what tranny i will get yet. i will be running a 275 55 17 rear tire. i was hoping someone can help me with what gear to put it in, and if i should install a posi unit while i got it apart. i want to run the trans that will come with the motor that way i will be plug and play with the wiring. this is all new to me as you can tell, any help would be great thanks again, Daniel.

Re: rear end help
 

How do you plan to drive it?
2x, or 4x?
Tire/wheel sizes planned?

Re: rear end help
 

sorry bout that, it is a two wheel drive truck that is going to be street driven. motor is going to be totally stock with ac.

275 50 17 tires in the rear.

Re: rear end help
 

I'm soon to be doing a 4.3 w/4l60E. I had planned on using the stock 373's but if I were taking the rear apart I would go with a posi and 354's or 308's to take advantage of the better milage the 4.3 gets. With the 5.3 you have over 100 hp more than the SBC so no need to keep the 373's if you in there changing gears.

Re: rear end help
 

You need to know which transmission you have first. It makes a difference in the gear ratio choice. As far as adding a posi unit, it is just a matter of dollars. Find a good professional to guide you and do the installation for you. This is not a job for a novice.

Assuming an overdrive transmission, I would stick with the 3.73 gears. They should put you around 2050 RPM @ 65MPH. The 3.08s would drop you to under 1700RPM and you don't want that. It sounds like it would be good for mileage, but it isn't. It is too far below the optimum cruising RPM, the transmission doesn't like it either.

Re: rear end help
 

3.73. That is what the towing package comes with and the 4L65E that should be with the motor. With the .70 OD of the trans you have a 2.611 effective gear. Which is plenty good for economy.

Re: rear end help
 

a limited slip is a good idea if you will take it to the track or you plan on towing a bunch. If it is just a cruiser, then you wouldn't need it. I don't think you need an active locker.

Re: rear end help
 

well i got it on the bench(center section) and it has 43:14 on it. so i guess i divide the two and get 3.0714286. i have a 308 rear end then, correct? so i have to start over completely. anyone recommend a good shop to setup the rear for me? looking at it i do not want to tackle it, let the pros do the job.

i think i am going to do 373 gears like noted before.

Re: rear end help
 

Pyle Brothers
2402 Cedar Bayou Lynchberg Rd
Baytown, TX 77521-1638
(281) 421-5878
pylebros.com‎

Narrowed my rear at a reasonable price. hey do a lot of racing rears

There is also a place called 249 drive train service on 249

Re: rear end help
 

ok guys, one more question. what parts do i want to buy, (not cheap stuff) for the rear. i have been reading that the eaton carrier is the best because they were factory installed. i want a limited slip just in case i go high horsepower in the futre. what gears and rebuild kit do yall recommend. i want the good stuff so i only have to do this once. thanks for all the help. daniel