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Old May 21st, 2017, 04:20 PM
POWERSTROKE POWERSTROKE is offline
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Default Re: 1965 gmc best tranny mate to 350

Quote:
Originally Posted by Ed Snyder View Post
A 305 would have no trouble pulling a small camper. Whether or not it would be "screaming" at 65 would be totally dependent on rear end ratio and tire diameter, both of which can be changed to suit your needs.
The day I ordered my '87 F-150 I test drove a truck with 300-6 and 4 spd overdrive with 3.08 gears. It would run about 45-50 in 1st, but shifting in the O/D 4th stopped any semblance of acceleration. I had driven a '78 F-150 300-6 and NP435 & NP-205 T-case with 3.55 gears for seven years and 95,000 miles. I went with that Exact same drive train with the changes FMC had made like the 8.8" rear axle in place of the 9", and Twin Traction Beam Dana44 in place of the Monobeam Dana 44. With the creeper low gear you could crawl around at an idle easily, trailer, or mud and snow would be no problem. Second gear was normal starting gear good for about 15 mph, 35-40 in 3rd gear and Tach would read about 2600-2700 at 65 mph in 4th, returning about 12-13 mpg. Traction-loc was not available with 3.08 ratio. That would have helped mpg at Interstate speeds at the expense of having to use low gear to crawl around and really slow acceleration in 4th gear. Trailer towing in 4th would have been very small. The '87 EFI engine was rated 145 hp, vs the carb'd engine rating of 120-125hp, I think installing a 5-speed would be the best solution. The over-drive 5-speed for the half ton Ford barely survives running around empty, the ZF used in the bigger trucks is huge!. SON's buddy in high school had about a '92 Work Truck C1500, 4.3L 5-speed, wide ratio. If that could fit the 305 V-6 that would allow towing in most conditions and good cruising at 65+. Just not enough gears in a 4-speed, but many good 5&6 speeds available now.

My current truck I scratched around and figured gearing for months before I finally ordered it. After wearing out two F-150s that had too many low gears and not enough of a high gear I wanted something that would crawl and fly. The 5-speed ZF manual is considered a close ratio but I think it's pretty wide ratio actually. In high side of T-case I can idle at 600 rpm at about 3-4 mph in low gear, and can accelerate up to 2500 rpm in 4th to almost 65 mph and cruise at 67 mph at 2000 rpm in 5th. 3.55 axle gears and 32-33 inch tires. It's a 7.3L PSD, and I averaged about 19 mpg the first 240,000 miles before I semi-retired it to just towing & hauling, no commuting empty to/from work. The drive train would work great with a 401 V-6 providing the motivation.
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