Are the XY plates the same between the V3 and the V4?
Are the linear rails the same length between the two?
Any other major differences I need to be aware of.
Really hoping that I can 3D print all the upgrade parts that I need, minus the strut plates and use all the existing hardware that I have on my V3.
Seen upgrade kit @ LowRider v3 to LowRider v4 hardware upgrade kit – V1 Engineering Inc, LR4 is a great cost effective gift to LR3 owners, especially if they’re able to print their own parts.
No, the XZ plates are different.
Yes. But leadscrews are different, see upgrade kit.
If self printing, ensure your 3D printer is well calibrated, search forum for Calilantern references. LR4 has more 3D printed parts, and several that must fit well together, so tighter printer tolerances are needed for a great Assembly experience.
Consider cutting LR4 Struts, and XZ Alu plates even, using your assembled LR3 before upgrading.