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  1. The seal on my tranny where the driveshaft comes out is really starting to puke oil. It’s always been wet but there’s a puddle when I park. Does anyone have any advice or information on changing that? I’m a pretty mechanical guy but is this something that has to be timed when it’s taken apart or is it relatively simple. On a ‘79 RS686LS with the duplex. Thanks
  2. Paul nailed it right on the head. You get into thinking one thing and wind up getting another. Just like everyone else said, high mileage isn’t a huge deal if it’s been maintained reasonably. Whenever you go look or drive a truck just make sure you get it good and warm and keep an eye on oil temperatures and water temps. An older mack will hold together and if you learn to work on it then you’ll be alright. Just keep you some money set aside for repairs because there WILL be breakdowns. Whether the trucks got 5,000 miles or 5 million miles. It’ll work out like it’s supposed to
  3. Just for curiosity sake, what oil are you guys running in older Mack trucks and why?
  4. Hey fellas, got a leak on an endt676 motor on a 79 rs600 between the oil cooler and the water pump. Is that as simple as pulling the cooler off and replacing the gasket? What are the odds that that turns into a pretty major repair? Comin from a newer gold dog owner.
  5. Based on driving it, it sure seems more like the 350 than the 300. Although that doesn’t mean someone didn’t play with the injection pump to squeeze some more out of it. Truck is powerful that’s for sure. Definitely got mack camelback in the rear
  6. I dove off in the same creek as you. Bought a 79 rs686 with 370k. Paid 12 for it and gonna put it on the road. Drove it 3 hours home, hauled 4 loads of crushed concrete with it the other day, got a tad bit of blow by but a strong truck none the less. Been tinkering on it some mainly just cosmetic and minor air leaks. New batteries that type of thing before I dedicate her to work for 10 hours a day. The good older trucks are out there. Not knowing any history on it does kinda suck but a wore out old mechanical one can be fixed with a wrench if you have any sense, no computer knowledge required. Dive off in there ol son it’ll work out. 👍🏼
  7. Hmm that’s interesting. Preciate you fella
  8. Got another one for you mackpro, RS686LST46760 title shows it as a ‘79
  9. What does a rebuild kit for the motor in these older simple trucks? Is it just as far as you wanna go the more expensive or can you buy all the parts in a kit?
  10. Hmm. I think the frame is steel judging by some kind of bracket that used to be there that got cut off with a torch 😂 nothing major I’m sure. Thanks for the input 👍🏼
  11. looking at buying a 1980 RS600l, 6 speed with i think an E6, ive spent a bunch of time around r688's and rd's of all kinds but id never heard of any rs. Ive done some reading on here about them but im curious what kind of frame difference they have compared to their cousins. is an rs double framed and stout for dump truck work? its a 6 cylinder only difference i can find on the motor is its got 3 lube filters instead of two, which is a plus for my opinion. just looking for additional information on these workhorses. Thanks!
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