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nail pounder · 09-08-2017, 02:38 AM

Just my .02¢.I had planned on a rear end swap for my 66 C20 but after putting the size tires I wanted (31"), and having a 5 speed I was totally happy even with it being a 4.56 rear end. At 80 mph it's at 2600rpm. On my 58 knowing what I now know, I went straight to a 700r4, & with 235/75/15 (28") tires the 3.90 rear end is just fine. At 80 it's right about 2600rpm as well. The point I'm getting at is you can't go wrong with an overdrive trans and the cost may be about the same. Obviously if one or the other is failing do that first but you will lose your off the line giddy up with some of those gear ratios.

09-08-2017, 02:38 AM	#29
nail pounder Registered User Join Date: Aug 2014 Location: Fallbrook CA Posts: 453	Re: Transmission / rear end set up Just my .02¢.I had planned on a rear end swap for my 66 C20 but after putting the size tires I wanted (31"), and having a 5 speed I was totally happy even with it being a 4.56 rear end. At 80 mph it's at 2600rpm. On my 58 knowing what I now know, I went straight to a 700r4, & with 235/75/15 (28") tires the 3.90 rear end is just fine. At 80 it's right about 2600rpm as well. The point I'm getting at is you can't go wrong with an overdrive trans and the cost may be about the same. Obviously if one or the other is failing do that first but you will lose your off the line giddy up with some of those gear ratios.