I currently have XR drives with IMCO extension boxes. The XRs are the older style with the large u-joints and the coupler yoke has the extended shaft for the extension boxes. I’m switching to the new style swept back XZ drives with the smaller u-joints. Is it an option to swap out the smaller u-joints that came with the XZs and install the large XR u-joints on the XZs so I can reuse the extended shafts? Or is my only option to buy new yokes with the extended shaft that will fit the smaller u-joints that came on the XZ drives?

I know the newer XRs have the smaller u-joints as well so I’m guessing that I’m not the first person to run into this issue, but I couldn’t find any threads on this topic.

There are u-jounts that have different size cups for this reason. As long as you know the diamater of each set of cups and the lenght from cup ends you can have a jount matched up at a bearing/belt/pulley distributor or a driveshaft shop.

To get new shafts is expensive opposed to a semi-custom u-jount, prices on IMCO extention box shafts is $$$.

As mentioned I believe there are 3 different sizes out there. Why are you going from XR to XZ?

From what I’ve learned, the only difference between the XR and the XZ drives is the upper gear set. The X/XZ gears apparently last longer since they are not prone to pitting, but will break easier if you frequently get a lot of air or like doing hole shots. We boat on inland lakes and get on plane easy so that will not be a problem.

I appreciate the replies. I’m still wondering if I can just swap the entire u-joint assemblies without having to replace anything else?

Easiest way would probably be to find a combo U joint.