My 850D is a long track and has an extension tube on the piston for each idler yoke. The piston has a reduced pilot that fits into a pilot hole in the extension tube. The extension tube/extension joint on both sides are “bent”. The extensions enter the recoil unit at an angle. I won’t know the extent of the repairs required until I get everything apart. Would it be acceptable to align everything and weld the extension tubes to the piston? My parts book shows the long track 850Ds having a longer one-piece piston instead of the extension. It doesn't even show the extension tube design. I would weld it in intervals so as not to impact the hardened piston. The 850Es and 850Gs used the extension setup like my 850D. It was probably a cost reduction.
More than likely your D was a late production machine before they switched to the E series. That being said, you could weld the tube to the piston but why would you want to? The extension tube was just a cost cutting measure kind of like not putting grease fitting in the dozer blade cylinder bushings on the D series. I don't think the tubes were supposed to be bent though, I can't remember that though.
Thanks, Coy. The joint between the piston and the extension tube is bent. The extension tube enters the recoil assembly at an angle and seems to be "bound up". I may be able to repair the extension tube after I get everything apart, but it would be simpler to realign them and just weld them together. The pic is from an 850E. The pilot looks pretty short. This situation is on both sides.