








flathead drivetrain
______1500rpm_____ 2000rpm ______2500rpm
1st _____11_________15___________19
2nd______19________ 26 ________ 32
3rd_______30 _______ 40 ________ 51
4th______45 _________61 ________ 76
using the SROD with 3.07, 1.72, 1.00, 0.70 w/3.75 gears
_____1500rpm______2000rpm______2500rpm
1st___11________ 14 ________ 18
2nd___19________ 26 ________ 32
3rd ___33 ________ 44 ________ 56
4th ___48 ________ 63 ________ 79
Here is the calculator I used.
Gear Ratio Calculator
Almost looks like a wash, Either would work, the overlap, how does that look?
Here's the factory 3speed with 2.78, 1.62, 1.00, w/4.25 gears
_____1500rpm______2000rpm______2500rpm
1st___11________ 14 ________ 18
2nd___18________ 24 ________ 30
3rd ___29 ________ 39 ________ 49
Here's the factory 3speed with 2.78, 1.62, 1.00, w/3.75 gears
_____1500rpm______2000rpm______2500rpm
1st___12________ 16 ________ 20
2nd___21________ 27 ________ 34
3rd ___33 _________ 44 ________ 56
Here's the factory 3speed with 2.78, 1.62, 1.00, w/3.50 gears
_____1500rpm______2000rpm______2500rpm
1st___13________ 17 ________ 21
2nd___22________ 29 ________ 37
3rd ___36 _________ 48 ________ 60
Here's the factory 3speed with 2.78, 1.62, 1.00, w/3.25 gears
_____1500rpm______2000rpm______2500rpm
1st___14________ 18 ________ 23
2nd___24________ 32 ________ 40
3rd ___38 _________ 51 ________ 64
rumor has it the cases of the T4 and T5 are the same.
If it was my truck my choice would be to find a 3.50 3rd member for the 9 inch and put it in the truck.







