Question: to replace this part, do I need the regular 39-253LBor the Low Profile 39-438B? And what other parts go along with it?
Truth dual arm operator still mount 41011




Looking at your operator, you appear to have our 39-253LB. This is based on the fact that you have a bare peg at the end, whereas on the 39-438B the black guide is permanently affixed.
That said, it's entirely possible you had the black guide on the 39-438B and it simply broke off. That's not something I can verify for you, though. You'll have to check the original guide to verify its style. For reference, the 39-253LB is made to work with the detachable 39-529 (sold separately).
The compatible handle and cover would be our 39-451. We also sell the 39-546 bracket, but you can also reuse the original.
If you haven't seen it already, we actually have a video on how to tell these two products apart. You can see this on their respective store pages in our catalog. I'll also share it below for your conveninece.