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im doin a 12v cummins conversion to my 85 chevy one ton.. i would like to know if my tubro 400 would handle the power of a cummins.. and also would i be able to drive the truck 60mph or more with the 3 speed tranny..my truck has 33's and has 410 gears..i would like to know how to figure out what the rpms would be at the final gear.. it would be alot easier to use my existing transmisson without trying to figure a transmisson to use and trying to adapt to my tcase. Thank you for the help
 

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TDG Mafia Member #56
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85chevyk30 said:
im doin a 12v cummins conversion to my 85 chevy one ton.. i would like to know if my tubro 400 would handle the power of a cummins.. and also would i be able to drive the truck 60mph or more with the 3 speed tranny..my truck has 33's and has 410 gears..i would like to know how to figure out what the rpms would be at the final gear.. it would be alot easier to use my existing transmisson without trying to figure a transmisson to use and trying to adapt to my tcase. Thank you for the help
No and no. I have seen a few th400 set ups behind healthy 5.9's and they don't live. You will have to buy a good torque convertor and keep the engine pretty mild to keep the Th400 alive.

You won't see 60 very long with 4.10's. Your rpm's at 60 would roughly be 2572. At 70 they would be 3000. You will need to change your gears to like 3.08 like the first gen dodges with no OD.

Here is a link to a rpm calculator. http://www.ringpinion.com/Calc_RPM.aspx
 
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