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I'm currently in the process of converting my 1969 F-100 2WD longbed from manual to a C4 automatic. I spoke with a shop about shortening the front drive shaft and they want the length from where the u-joint sits in the flange on the transmission to the center of the carrier bearing. I found on another forum that my current front coupler is 33-19/32" and need to be shorten to 31-63/64" but didn't find where they were measuring from and the shop already has the driveshaft so I can't compare it to mine. Can I just tell the shop to take off the 1 39/64" from the tube or does anyone know what length they are asking for?
As the shop said they want from the Ujoint seat to the center of the carrier bearing what is so hard to get under with a tape measure and get what the truck has?
What if you guess and use anything you find off the web, the shop makes it to that size and you find out it will not work as it is too long or short?
The shop is not going to fix that for nothing as you gave them the size so do you want to pay them twice if it is not right?
If you are looking to throw money away I will send you my address in a PM so you can send it to me
I did that to my 81 F100 when I installed the Range Splitter over drive as it moved the transmission back 7-1/2" but did not take their word for it I measured to make sure and gave the shop that measurement. Now mine dose not have a carrier bearing 1 shaft from trans to rear axle. I also knew the weight of the truck has to be on all 4 wheels when taking the measurement.
I dont think you have to worry about that but you may want to put it on all 4 wheels to make sure.
Dave ----
I haven't had the chance to put in the new transmission yet so I don't have a way to get the measurement yet. I hoping to get the driveshaft done and get ready to put in with the transmission. The old one is already out too so I can't compare measurement points of what I have found. I'm just seeing if anyone has done this and knows what measurement is accurate.
I would wait until you get the transmission installed. On my transmission swap, I was able to measure how much shorter it needed to be. Also, I the shop replaced the connecting u-joint, pressed on a new carrier bearing, and balanced the drive shafts.