Rear Main Driveline Length

I'm another new guy to the early Broncos. Always wanted one and finally bought one about a year ago. It's a '72 bored 30 over with aluminum heads roller rockers and hydraulic 512 cam and lifters. The engine builder says it's somewhere between 385 and 400hp. Sounds wicked with the flowmasters. Lobes beautifully idling at 750rpm. I had this same engine builder do an overhaul on the whole rig while he had it. The truck is 100% brand new mechanically. Everything but the front and rear diffs and transfer case. They were inspected and in great condition. Power steering and power disc brakes in front have been added. New Centech wiring harness will be installed next week. When this truck is done it will be my daily driver. Here's my question: How do I determine the proper length for my rear main driveline? There's no lift but all new springs. The driveline that was on it twisted clean through at the tube. Broke in two right in the middle and each end twisted in on itself so I can't really determine it's original length. Bought a used one, already reinforced and balanced at a junk yard, but seems like it may be an inch or two longer. Right now I have the truck on jack stands with the rear axle hanging free. I've measured the length of driveline that now sticks out of the slip yoke. Now what's the next step in determining if it is the right length? How much travel should there be between fulling extended, sitting parked, and how much room should there be available while sitting parked? If it's too long it will slam into the u-joint at the rear differential, right? Any input is appreciated. This is a really awesome forum, btw.

Hi Jim...., welcome..,

Toms Bronco Parts right there in OR. ... Or., Wild Horses in central Cal. have drawings on how to measure that...

However.. "NO LIFT" = Stock lengh Dr. shaft...new springs or not...!!

BUT.., if you intend to use most, or all that HP....you'll be better served stopping at your local drive line shop., & have them set you up with some heavy duty shafts & U-joints..... Or shop those Co's above & do that yourself.

BTW do the measurements with wheels down on the deck....

Thanks, bully.. good info.. i called Tom's. I knew of them and got most of my stuff from them. I didnt realize they would have the free tech support. They told me what i needed to know, so much obliged

Just an FYI for ya. ANY of the vendors are happy to give free advice, if you buy from them or not. Especially when it comes to technical stuff that is off the wall and you can't find the info. So don't hesitate to call them if you can't find the answer online.

ANY of the vendors are happy to give free advice, if you buy from them or not. Especially when it comes to technical stuff that is off the wall and you can't find the info. So don't hesitate to call them if you can't find the answer online.

Yes call all the venders for info and parts info thats how I got started with these (uhhh unique) trucks most will hang with you on the phone while you measure and send pictures of the part you need so you can understand what you want too do. The economy is bad they want too sell parts use them to the fullest..They are there for you and want you too call !

PS Big order ask for a discount on product and shipping!!!

BBB

ANY of the vendors are happy to give free advice, if you buy from them or not. Especially when it comes to technical stuff that is off the wall and you can't find the info. So don't hesitate to call them if you can't find the answer online.

Yes call all the venders for info and parts info thats how I got started with these (uhhh unique) trucks most will hang with you on the phone while you measure and send pictures of the part you need so you can understand what you want too do. The economy is bad they want too sell parts use them to the fullest..They are there for you and want you too call !

PS Big order ask for a discount on product and shipping!!!

BBB