Minuit

Look ma, I'm on the Google!

As the XJ improved mechanically, it went downhill stylistically. Basically at the same time, with a brief peak in 1987 and maybe 1988 when you could have the 4.0L engine and an 80s-tastic interior and exterior treatment at the same time. Minor exception given for the 90s woodgrain + leather interiors. * this is the opinion of an avowed 97+ hater. Your mileage may vary.

I've driven my truck a grand total of about 5 miles with the exhaust dumping after the converter right under the cab and that was enough for me. I would class it as "hearing protection required" loud and I'm quite glad I just had to get to the parts store to get what I needed to hook my muffler up. We could go into the fluid dynamics of exhaust systems and I could tell you that you may or may not lose a handful of horsepower and you may or may not notice that, but by no means will it hurt anything. As long as your O2 sensor is hooked up, have at it. You'll probably hate it though. It's something every car guy should do for fun at least once.

Almost all of them are #8 sheet metal screws. Most are your garden variety pan head in various lengths, but some are these, which I think you should use wherever possible: https://www.mcmaster.com/sheet-metal-screws/phillips-flanged-extra-wide-rounded-head-screws-for-sheet-metal/ I grab those from every XJ instrument cluster I come across. I've got a big bag of them and everywhere they fit, I use one. They're much nicer quality and are easier on the plastic.

Anyone want to send me one of these tachs for research purposes?

I see no reason why you wouldn't be able to. You'd need to calibrate it, but that's easy enough with the appropriate equipment.

I'm at least 90% sure that the back of the unit is for the front brakes.

Those look like carbon composition resistors, which have a bad habit of drifting (usually upwards) in value as they age. Might be worth checking their actual value with a meter against what they're supposed to be (see resistor color chart). Shouldn't need to pull them out of circuit to do so unless they're in parallel.

...and ideally it'll be a Mopar sender you replace it with, if you can still find them these days.

Old style fronts on the rear of the MJ are the way to go IMO:

Have you connected a mechanical gauge in place of the oil pressure sensor (near the oil filter) and confirmed the gauge readings?

Is this the one I'm building the radio for?

Regardless of whether your truck came as a radio-delete or not, the wiring exists at the dashboard for the radio to plug into and out to the kick panels for the door speakers, and to the speaker locations for the rear speakers. You'll need to run the wiring from the kick-panel area out to the doors, or just get that section of the harness from the junkyard. Here's an aftermarket radio harness adapter for an 87: https://www.crutchfield.com/p_120701000/Metra-70-1000-Receiver-Wiring-Harness.html?tp=2977 The factory speaker locations consist of: Two tweeters behind the "vents" in the lower dash installed with special brackets. This location was only used with the XJ-only "Accusound" package, but some aftermarket tweeters will fit in the brackets. You might be able to get up to 3.5" speakers in here, but I don't recommend it. Two 5.25" speakers in the doors; nylon nuts should be present in the doors to install the speakers with sheet metal screws. If not, they can be gotten from the hardware store. Someone on here might be able to help you with getting the appropriate door cards so you won't have to cut into your originals, or you could get lucky at the junkyard - not likely since an 87 can't have a grey interior, which is the most common color BY FAR. Two 4x6 speakers in special Comanche-specific brackets in the lower B-pillar. If your truck was a radio delete, or came with a base model radio, don't expect to find the brackets there. Due to the small size of the Comanche cab, rear speakers won't be a strict necessity (and depending on your setup, you may find your system sounds better without them), so don't feel too bad if you don't have or can't find these brackets.

The ones on mine are Metri-Pack 150, unsealed 3-pin. But I think they used Molex at one point.

AMP MIC Mark-II. Also used in radios. The pins crimp very well with a standard ratchet crimper. https://www.corsa-technic.com/item.php?item_id=1142

The factory standard equipment was just the low tone, I think.

I swear I saw a post in here asking about new tools... here's one of mine. Runs from any 12-24DC power source, or a USB-C power bank. Configurable temperature (and options for everything else you'd want), and open source firmware. Heats up in 15 seconds using a 19V laptop power brick, which is not as fast as my expensive Pace station but certainly quick enough. And the best part? It cost $40 with one tip included.

Horns.

Correct. Coolant will pool on the passenger side if the heater core is leaking. Also look for a sweet smell on the inside.

You could make half of this system with bastardized windshield washer sensors (assuming, that is, that they wouldn't get eaten by brake fluid). I think some 4.0 oil pans even have a bung for an oil level sensor. The only thing that seems all that hard at a glance is the brake pad sensors which I could live without.

I was just thinking, that looks uncannily like the washer fluid sensor - I happen to have a few of those in the attic.

I could totally make that... evil thoughts

Attention all JRE friends and customers: You can officially say that I've come out of retirement. I will now be offering the full range of products and services until further notice. Please note that due to demand for my services, it may take time before I am able to complete your order. At the moment, things are moving along swiftly, but my available time is subject to change. Additionally, I am no longer adhering to a waiting list - I will complete orders as it is practical for me to do so, not following a strict order. Therefore, if your order involves a particularly difficult request or particularly rare parts, it may take even longer than usual. Additionally, the website has been updated with current pricing. Unfortunately, a ~25% increase in many of my supplies has caused prices to increase correspondingly. Thank you for understanding.

You're finding all the good stuff lately! Let me know if you need some help with that. One of these days I'm gonna have one of my own.

Attention all JRE friends and customers: As of today, all wiring harness adapters and Do-It-Yourself Kits, are now once again available for purchase for $50 shipped within the continental United States. The website will soon be updated with the new prices. For other inquiries, such as purchasing a radio or having repairs done, please contact me via this page, the website, or my radio-emporium email address. Thanks, Jeremy