Dennis brown Posted December 9, 2022 Share Posted December 9, 2022 1982 f100 short box fender side, just pulled from 19 years in my barn. Rebuilt 351w installed a few years before storage. Otherwise all original rwd truck. Plans are replacing stock 3 speed with np435, and 275 rear gear with something in range of 373/411. Link to comment Share on other sites More sharing options...
FuzzFace2 Posted December 9, 2022 Share Posted December 9, 2022 So a "short box fender side" would be a flare side? Lets see some pictures as we love pictures. The 3 speed is that on the tree? If so dont trash the parts in the column as they are hard to come by and some are looking for parts. I dont have anything with the NP435 or and of the granny first gear transmissions but got to ask what will the truck be used for that you want to change the rear gear? Also unless you have an over drive unit to use with the 3.73 / 4.11 gear I would not go much lower than 3.50's if I was to check it at all. I have a 300 six with the NP435 and 2.75 rear gear and between the motor & rear gear it will never be a stop light killer but gets the job done. BTW I do have a over drive unit and still dont think I would go lower than 3.50 gear set but what I use the truck for the 2.75 work just fine. Dave ---- Link to comment Share on other sites More sharing options...
mat in tn Posted December 9, 2022 Share Posted December 9, 2022 So a "short box fender side" would be a flare side? Lets see some pictures as we love pictures. The 3 speed is that on the tree? If so dont trash the parts in the column as they are hard to come by and some are looking for parts. I dont have anything with the NP435 or and of the granny first gear transmissions but got to ask what will the truck be used for that you want to change the rear gear? Also unless you have an over drive unit to use with the 3.73 / 4.11 gear I would not go much lower than 3.50's if I was to check it at all. I have a 300 six with the NP435 and 2.75 rear gear and between the motor & rear gear it will never be a stop light killer but gets the job done. BTW I do have a over drive unit and still dont think I would go lower than 3.50 gear set but what I use the truck for the 2.75 work just fine. Dave ---- absolutely keep the intended use in mind. there is no "one size fits all approach". have a "purpose built" mindset and you should be happy but keep realistic too if looking for high speed or high mpg. Link to comment Share on other sites More sharing options...
Ray Cecil Posted December 9, 2022 Share Posted December 9, 2022 So a "short box fender side" would be a flare side? Lets see some pictures as we love pictures. The 3 speed is that on the tree? If so dont trash the parts in the column as they are hard to come by and some are looking for parts. I dont have anything with the NP435 or and of the granny first gear transmissions but got to ask what will the truck be used for that you want to change the rear gear? Also unless you have an over drive unit to use with the 3.73 / 4.11 gear I would not go much lower than 3.50's if I was to check it at all. I have a 300 six with the NP435 and 2.75 rear gear and between the motor & rear gear it will never be a stop light killer but gets the job done. BTW I do have a over drive unit and still dont think I would go lower than 3.50 gear set but what I use the truck for the 2.75 work just fine. Dave ---- Dave, what OD unit you running? I see AA OD in your signature but don't know what that is. Link to comment Share on other sites More sharing options...
Ray Cecil Posted December 9, 2022 Share Posted December 9, 2022 absolutely keep the intended use in mind. there is no "one size fits all approach". have a "purpose built" mindset and you should be happy but keep realistic too if looking for high speed or high mpg. What are you building the truck for Matt? Is it a Flareside? Chevy used the term "Step Side", and Ford uses "Flare side". I've never heard of "short box fender side". Although, it sounds like you are describing a flareside as Dave mentioned. Link to comment Share on other sites More sharing options...
mat in tn Posted December 9, 2022 Share Posted December 9, 2022 absolutely keep the intended use in mind. there is no "one size fits all approach". have a "purpose built" mindset and you should be happy but keep realistic too if looking for high speed or high mpg. What are you building the truck for Matt? Is it a Flareside? Chevy used the term "Step Side", and Ford uses "Flare side". I've never heard of "short box fender side". Although, it sounds like you are describing a flareside as Dave mentioned. i generally build mild hotrods but im doing a mpg minded 83 f100 with a 5.0 with a wide ratio aod and a 3.31 final drive and im also resurrecting an 81 camper special intended to be a towing vehicle for my trailer. it has the 351m with a c6 and a 2 bbl. each has its own purpose. Link to comment Share on other sites More sharing options...
Dennis brown Posted December 10, 2022 Author Share Posted December 10, 2022 So a "short box fender side" would be a flare side? Lets see some pictures as we love pictures. The 3 speed is that on the tree? If so dont trash the parts in the column as they are hard to come by and some are looking for parts. I dont have anything with the NP435 or and of the granny first gear transmissions but got to ask what will the truck be used for that you want to change the rear gear? Also unless you have an over drive unit to use with the 3.73 / 4.11 gear I would not go much lower than 3.50's if I was to check it at all. I have a 300 six with the NP435 and 2.75 rear gear and between the motor & rear gear it will never be a stop light killer but gets the job done. BTW I do have a over drive unit and still dont think I would go lower than 3.50 gear set but what I use the truck for the 2.75 work just fine. Dave ---- Truck was originally 3 on tree, removed linkage to make room for headers on 351w, and put in a floor shifter for the 3 speed. Np435 is from my 84 f150 which was junked. I like the 4 gear better. Roads that I use in western mountains of Maine are narrow,twisty,and hilly, better to have some gear to enjoy them. Pictures to come. Link to comment Share on other sites More sharing options...
mat in tn Posted December 10, 2022 Share Posted December 10, 2022 Truck was originally 3 on tree, removed linkage to make room for headers on 351w, and put in a floor shifter for the 3 speed. Np435 is from my 84 f150 which was junked. I like the 4 gear better. Roads that I use in western mountains of Maine are narrow,twisty,and hilly, better to have some gear to enjoy them. Pictures to come. Maine? I was just there in September. love it there but hey it gets kinda cold. another point about purpose building, I guess. I drove there in my flare side because the od makes it very comfortable and it gets the best mpg of the group. About 19 mpg on that trip. Link to comment Share on other sites More sharing options...
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