89 MJ

That's super strange. I've never noticed that before, but I also never really paid attention either. Now you've made me start watching

A 3 speed with a 4.0 you say? Does is the transmission computer controlled or is it just kickdown linkage? What type of transmission is it? I don't think that you are from the US, but here in the US, all 4.0 Comanches with an automatic transmission came with the AW4 4 speed automatic. Other AMC and Jeep models could come with 3 speed autos. In AMCs, I know this was the TF998 in the late 70s.

Just a guess, does that show up once a thread reaches 2+ pages?

People that have to experience emissions testing will not pass without EGR. If you do not have to go through any sort of emissions testing/inspection, there is no downside to deleting it that I have heard. All it does is feed your engine's waste right back through it, reducing efficiency.

I'm going to guess purely by the fact that it is a Crown part and that it is an aftermarket piece that it is junk. Thin metal and poor fitment.

Other than the hard brake pedal, that’s a great idea. Exactly what I’d do.

No such number in my 87-90 parts catalogue

Congratulations! Now get out there and make some money so you can spoil the truck!

To be honest, I was going more off of the smoke coming from that area than the acceleration. I've seen stuff like that come out of brake boosters when unhooking them before. I'll be honest, I haven't watched the video yet, but I will when I have better signal.

About the only way I can think of would be a combination of an old, brittle hose and the acceleration causing the engine the engine to torque over farther and breaking the hose. Its a stretch though.

Since you posted this on the AMC forum too, they might ask you to add the T10 and Super T10 transmissions. I think those could be had in close and wide ratios too, but I am not completely sure on that.

Your best bet might be uploading it to youtube and then linking the video here. I would carefully inspect vacuum lines, including the one going to the brake booster.

That’s awesome! I was actually looking for the Muncie M21 on there the other day for some reason.

Probably transmission cooler lines

No need to care, though you could improve it with a brass punch and a hammer where the steepest part of the bend is.

My honest opinion is to use an LS and an auto from a 99-02 GM truck and trim that harness down. More power and likely better fuel economy than your 4.0 would ever do. If you like the 4.0, 91-95 HO would be a good option, 89-90 Renix would be a good option, and then the 87-88 Renix. I ranked them that way because a lot of people prefer the HOs, then the 89-90 Renix did not have the C101 connector under the hood and they had a better ECU that makes a little bit more power, and finally the 87-88 harness which has the C101 and the less desirable ECU.

Hmmmmm. I’ve seen similar braces that go from the front fender to the firewall on a CJ7.

Have any pics handy?

April 2026 - Crispy The 1989 Long Bed Dually Owned by @88mjsally Build Thread- Year/Model - Dually Swapped 1989 Pioneer Drivetrain- High mile 4.0/ 2wd auto aw4 currently but I have plans to swap to a 5.3 LM7/AX15/np321 hopefully later this year. Currently has a HP d30 from a 1996 Jeep Cherokee up front and a 1995 ford F-350 cab and chassis dually sterling 10.25 in the rear. Stock drive shaft from a 2wd 2.5 manual mj with a 1310/1350 ujoint. Cooling- Stock from a newer Cherokee with the open cooling system. 97+ electric fan wired with a relay to a switch so it can run all the time. Electrical/Ignition- Completely stock currently Suspension/Steering- Front lift is a 4.5” rough country short arm kit. IRO adjustable track bar, rough country extended brake lines, 1.5” pucks on top to level/ account for the bumper and winch weight. Stock steering for now with new tie rod ends. Rear is stock springs and shocks with Barnes 4wd perches welded to the 10.25 spring over. Interior- Mostly stock interior with XJ buckets and a console. Newer grey ACC carpet and floor mats. Currently set up as a non tilt column shift but will soon be a manual transmission with a tilt column. Has a full gauge cluster as well from a XJ Brakes- Stock rotors and brakes from a 96 xj up front with rough country extended lines. Rear has the stock drums from the 10.25 and stock lines which hooked up perfectly to the mj hard lines. Rear proportioning valve has been deleted and it has an xj valve under the hood. Booster and master are from a 96 XJ with the same year pedal swapped in so I didn’t have to grind the booster rod. Brake light switch is for a C10. Lighting- New cheapie marker and turn signal lights up front with LED bulbs. Amazon LED headlights that are probably knockoff Truck Lights with a relay harness. Fog lights are ROLS from a limited XJ with an aftermarket harness. The rear is stock taillights with LED bulbs installed. Dually fender marker lights are for a newer Chevy 3500 wired into the running light circuit. Exterior- Mostly stock other than the dually fenders and front bumper. Crappy single stage paint job that needs to be resprayed pretty bad. Dually fenders came out of Florida from a truck that was being parted out. Fuel filler door was deleted so I used a boat filler neck which turned out pretty nice. ARB Front bumper was on my 2001 XJ for a while but I thought it would fit this build better. Has a 12k badlands winch in it and a roller fairlead with a flip up license plate. Wheel & Tires- Metric 32” mud tires up front on stock JK wheels with rough country adapters. Rear is stock 16” 8 lug ford steel wheels painted black with 32” skinny mud tires Best MJ story- So far with this truck I just like seeing the looks when people realize that it’s a Comanche dually which most people have never seen before. I saw one a few years ago and have been wanting one ever since so decided to make this truck into one CC is Awesome! Why? Great resource for the community with lots of great knowledge and help

IIRC, the Renix oil filter points up at roughly 45*. Sounds like you already have the HO one.

I concur with the other two said. There was a seam right there where the firewall overlapped the floor pans. More than likely, moisture got in there causing the rust you see. I would also bet that the rust is going to be much worse than you're seeing by the time that you pull the carpet up. When I got my truck, there was only a quarter sized hole visible from the bottom on the driver side. After pulling the vinyl floor covering, I needed the front half of the driver floor pan and a decently sized patch on the passenger side. That said, the trucks that had the vinyl floor covering instead of the carpet always seem to rust worse. I think your best bet is to pull the carpet and then we will be able to come up with a better plan how to proceed. It might just be a minor patch that needs to be made, it might end up needing a full floor plan replacement where you'll need the floor braces too. Thankfully, Key Parts makes both the floor patches and the full floor pans for each side and it seems that the fit is excellent. I think the biggest question is, how confident are you with your cutting and welding skills? Floors are a pretty important thing to have and they're not always the most comfortable thing to weld in. If you can weld them in and make them strong, its probably something that you can tackle. If you haven't welded sheetmetal before, I would probably find someone who has done it before.

I hope you told him to log on and find out

But on the bright side, his getting sorted out first means that it should be a lot quicker to get yours dialed in. This car should be a great reference.

New grilles installed. An appointment has been made to get new exhaust made. He also swapped a new accelerator pump in the car and played with the timing. The car is much more powerful now. It had 14 degrees in it, now it has 18 and it helped a lot.