Jump to content
Sign in to follow this  

Recommended Posts

Those are beautiful! I ran a 1988. If I was still in it, I would probably still kinda enjoy trucking. Well, at least I'd enjoy driving the truck, LOL

Share this post


Link to post
Share on other sites
On 12/28/2018 at 4:43 PM, mackey58 said:

Any RD tractors

I have a few RD tractor pics but no RD690 tractors that I can think of.

Share this post


Link to post
Share on other sites

Most Rd tractors were 688’s. Most of the time an rd tractor would be a heavy haul tractor and you would want the extra hp and gears.

  • Like 1

Share this post


Link to post
Share on other sites

Even an RD is good i think mine is rare.the built sheet said it was one of 3 that went to chicago mack for a customer but only bought 2

Share this post


Link to post
Share on other sites

Mines a em6 300L 7 speed pulls a 79 axle Framless every day since my boss found it in a shed in 2014.works on the lowboy once I a while but ya can't get in a hurry

Share this post


Link to post
Share on other sites
11 minutes ago, 1965 said:

What does the P stand for?

Suffix P is a platform chassis (single axle straight chassis).

  • Like 1

Share this post


Link to post
Share on other sites

Nice that's what I thought.there was a company here at one time called ganja construction .you'd see 5 or new mack rd s running the you'd go to chicago mack and see 3 or 4 new rd s that said ganna  specs on the sheet in the cab window 

Share this post


Link to post
Share on other sites

Can someone tell me what is the difference between an rd686 and an rd 690.  I thought it was just a year thing but now i'am not sure.   Maybe the 686 has only 6 speed and 690 has 7 spd or more Maxitorque gears.

Share this post


Link to post
Share on other sites

686 has the engine mounted intercooler, 690 has the chassis mounted intercooler in front of the radiator.

Share this post


Link to post
Share on other sites

I have a 1987 rd686 with the chassis mounted air cooler.  The em7 vs em6 makes the most sense. What confused me was several of these rd690s are before 1989 i thought that was when the em7 came out.

Share this post


Link to post
Share on other sites

J Hancock, thanks for correcting me. Although the distinctions between the 686 and 690 are kinda vague, your explanation makes the most sense.

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
Sign in to follow this  

Welcome to BMT!

...The world's best antique, classic & modern Mack Truck support forum! Founded in 2000, BigMackTrucks.com is the place to go for everything related to Mack Trucks!

BMT!

BigMackTrucks.com is owned and operated by Watt's Truck Center, New Alexandria, PA. This forum and it's contents are not affiliated with Mack Trucks, Inc. or Volvo Trucks North America.

×