85R688ST

Changed my User Name. Just FYI since I don’t have the RD690 anymore I just changed my user name to 85R688ST

I will definitely post some pictures when we get it back on the road. Presently we have it in the shop for a new turbo and CAC. I broke one of the turbo studs off trying to remove the turbo for the change out As you probably know these are stainless steel. It was broken off about 3/4” deep inside the manifold. We worked on it for 2 days and finally drilled most of it out. When I tried to run a tap in it the tap broke off. To make a long story short, I ordered a new manifold set and all new studs/nuts for the change out. Now I’ve got 2 of the high pressure fuel injector lines that won’t come out. I can get the jam nuts loose (finally) but when I try to back the insert that’s in the head out it just twists the hard line. I guess I’m probably just going to order a whole new set tomorrow for all 6 lines. After 40 years some of these parts just won’t come apart. Seems like everything we attempt we run into some kind of issues with stuck fasteners. Anyway, hopefully by the end of next week we will have the Bull dog barking again!!

Thank you Mowerman for your response. I will give them a call and look at the styling of those wheels. I’m almost through with the truck and I will upload some pictures when we are finished. It’s a beauty. I should have it out of the shop next week. It’s currently getting two new Remack differentials and a Remack 12 speed. $$$$

Hello everyone. I’m kinda new on the forum but have been following the forum for years. I recently purchased a 1985 R model and I’m in the process of a full restoration. It’s a R688ST Gold Bulldog with a 350hp E6 and a Mack 12 speed, TRTXL1070B. I would like to replace the HUGE steering wheel with a smaller one but definitely a MACK wheel. Any recommendations on year/ model of truck I should look for that will fit my 1985 model?? Any help will be greatly appreciated. Thank you, Jeff Crowl in Branson Mo

Here’s a few pictures I took of the bulldog today. My plan is to go through it a make a super nice rig out of her! We couldn’t get the door stickers off with the heat gun and they are not representative of the current owner. I’m going to try one of those eraser/buffer wheels. 208” wheelbase

We got it running today. Runs good but needs 4 new batteries which I expected. Cleaned the tag on the top of the valve cover. It is indeed an E6M. 7 speed transmission with the air shift for low, high and N which I assume is neutral?? Can anyone confirm what the position (N) would be used for??? I need a filter kit. Can anyone copy a post for the filter kit needed for this engine? Looks like it has 2 long oil filters plus one other shorter filter in front of the longer oil filters but it doesn’t look like the slinger filters I’ve seen pictures of?? Looks to only have one fuel filter on the other side of the engine up front on the passenger side. That’s the one I really need as I’m sure it’s needs some attention. Of course the number on it was not visible as I guess it was on the inside. Any help would be greatly appreciated!

Thank you sir! I’ll get a rag and some cleaner and see if I can find the tags. The previous owner thinks the ratio he ran was .417 and 38k# rear axles Do you think the 1990 model engine was designated a EM7 or just E7 ? And what was the difference ? Jeff

Can anyone help me with the rear ratio and weight rating from this picture below? It’s the markings on the top of the rear diff. The tag/label on the side of the diff is un readable. The previous owner told me it has the 300 maxidyne, 7 speed combo thanks