Thank you sir, maybe some day I will take a couple of these trucks to a show. Problem is, I can see every mistake and I know everyone else will see them as well. 

It’s a beauty. Lots of custom parts. Updating the power with things like a charge air cooler is a feature a lot of guys miss. The Cummins logo is a nice touch. I enjoyed watching this come together on the other forum. You should definitely consider bringing this to a show.

Just finished this build today. Nearly every part was modified/ replaced with 3D print or scratch built. 

Hi! For 1/24 and 1/25 scale truck parts, check Thingiverse, MyMiniFactory, Cults3D, and Printables by Prusa. You can also use CAD software like Fusion 360 or FreeCAD to design or scale parts yourself.

appreciate your in put ......I just presumed that finding info. on the Mack would be like my previous findings (dimensions) on the 60's era International Harvester DCO 405 Emeryvilles and VCO A 190's as well as the Ford C series cab overs....discovered volumes of useful information.   Looks like I will have to add 12 to 18 scale inches to accommodate the tank body...still undecided about adding a pusher axle.   

Sorry to hear your search hasn’t yielded much info. I unfortunately can’t offer specific as to wheelbase offerings, but I have stretched frames to accommodate bodies. I definitely agree that you can just place the tandems where they “look right”, and go from there. Sort of, “reverse engineer” the project based on what your eye tells you is right. That’s ultimately what you’re aiming to please - your own opinion of what’s realistic based on what is sweet to your eye.

I have a Mack DM 800 ,tractor version, that I need to increase the wheelbase on.  I have a 3-D printed oval tank that will be used with the build.   I have scoured the internet including Big Mack Trucks.com with no luck finding any wheelbase options for the DM 800.  I did find one spec sheet for the DM 800 showing multiple wheelbases, but the print was so small that any attempt to enlarge it only blurred it.  Mack has a fair amount of wheelbase info. on some of its other  models, but for some reason the DM 800 remains elusive.   My question is to those of you who have stretched a frame to accommodate a body (dump,flatbed, wrecker, etc. etc) do you just dry fit the body and stretch it so the the tandems are where they are suppose to be or is there something else involved.        

i was wondering if you can lower the suspension on a international lonestar truck 

This part is more of a personal preference from past experiences.  The AMT Ford C Series cab over is offered with a variety of bodies.... box truck delivery,trash truck and a flat bed,stake truck.  I am going to presume that all 3 bodies mount the same way to the chassis...I am only familiar with the trash truck...in that there are locating pins on the chassis and corresponding holes on the body.     I.M.H.O the trash truck body sits too close to the tires.  In the 1:1 world this is inviting a D.O.T enforcement inspector to pull you over for an inspection...either your overweight or something is broke on the suspension....either way it will ruin your day.  A good rule of thumb is aprox. 6" of clearance between the top of the tire and the bottom of the body ( box truck, garbage truck, flat bed. etc. etc.) with no load.  As far as the box truck and flat bed trucks go , I don't know if they sit any higher or lower than the garbage truck body....from what I can tell from pictures of builds, they have about the same clearance as the trash truck. I am going with 6 scale inches (6 m.m) of clearance. I needed to add 2.79mm. to get 6.6 mm.  The larger round tube is the spacer cut to 2.79 mm. It is Evergreen part# 224 1/8" tube (3.2 mm.)  it fits snugly over the pins on the chassis.    The smaller rod is the locating pin that fits into the bottom side of the body.  It is Evergreen part# 212   080" rod (2.0 mm.)  You will have to slightly open up the end of the Evergreen tubing to get the rod to fit inside.      I will fill in the area between the new spacers to illuminate the gaps.  6 mm. of clearance, right on the money.