My 70 roadrunner (383 auto) is missing its driveshaft. It is supposed to be 51.5 inches in length.

I have a spare 3.25 dia driveshaft which is a bit longer. It has small ujoints on front and rear (7260 diff yoke). My application uses a 7290 diff yoke.

I was going to shorten the driveshaft but have a couple questions about doing it

Did the 70 roadrunner use the big ujoint on the front of the shaft as well as the rear?

Would a good driveline shop be able to replace the ends with flanges that utilize the larger (7290) ujoints?

Yes, 7290 on both ends

Yes shops can change ends. But at that point a whole new shaft might be the same price.

Alternatively, get a conversion joint for the axle end.

Thanks for the info.

Headed to Drivline shop today.

Going on stock 383 with stock gears (3:23) for cruising and occasional power runs.

Mechanically, does it need 7290 ends or is running a 7260 up front and a 7260/7290 on axle a sound change? Any dis-advantage to doing so?

I've been running the small joints for almost 30 years on my car. No failures.


I don't have huge power or slicks

if if you are shortening AND and end change. I would be looking at all new shaft

What does the axle have in it.

If budget is an issue shorten it, get new U joints with the rear using a 7260-7290 conversion and drive it. It will be fine

[quote=70mopes

Mechanically, does it need 7290 ends or is running a 7260 up front and a 7260/7290 on axle a sound change? Any dis-advantage to doing so? [/quote] I've ran many mix u joint drive shafts in some of my old drag race cars that had 8 3/4 in them with the small 7260 U joint pinion yoke on them, same thing the other way with using a conversion U joint on a car that had the 7290 U joints on both ends driveshaft that we swap a third member into it that had the smaller 7260 pinion yoke on it, swapping the U joint was usually easier, faster and cheaper than replacing the pinion yoke to the 7290 type, especially on the "489 carriers"
buy the offroad H.D. solid U joints, not the stock OEM replacement type

Thanks to all for feedback. Much appreciated

I took shaft in to be shortened this morning. Decided to use a 7290 replacement yoke on rear to match 8 3/4 yoke and left the forward 7260 yoke and slip joint as is.

Get it back in a couple weeks.

i agree with Cab.
run the offroad solid joints without the grease zerk.

Depends on use. I've been running Precision joints since 97, grease em up and no problems

Damn near 30 years and they haven't been apart.

If he's building a drag car then sure go solid.