I started with the suspension on the kit.
Using the M2A2 ODS vehicle on display at the Minnesota Military Museum at Camp Ripley, MN I did a LOT of measurements all over the vehicle to help create accurate parts.
The M2 series roadwheels are unique: Gino once pointed out long ago that the M2 and M109 roadwheels do not have “rims” - the vulcanized rubber goes all the way up and around the rim edge. The rim also wraps inside the wheel a little bit, which modeled even though it cannot be seen without cutting the wheel in half. I did retain the ability to use the plastic grommets to mount the wheels on the arms, more usable but the backside of the inner roadwheels are not so correct. Oh well.
With the roadwheels done, I made some faux shock absorbers to represent these very obvious missing pieces on the kit. However, they are not a full fix…the roadwheel arms are molded to the lower hull, so it would take major work to fix. Not worth it in my mind, but they do the job well.
Return rollers are very simplified, so I made more detailed wheels with correct mounts. With the side skirts on, not really seen.
I did the idler mounts as something MUCH more realistic and created them so they the idlers are mounted staggered so they reflect the actual mounting on the vehicle. With this done, I made the idler so it was more accurate but without the ability to use the plastic grommet to attach it to the idler mount. Less easy to use (they have to be glued on) but so much more realistic.
The Tamiya sprockets are notorious for being incorrect, so I decided to take a crack at them. It took a LOT of work, but they eventually came out great. They fit the T-157I (Bigfoot) track well from many manufacturers (not every track tested) but they fit the Tamiya rubber bands, the AFV Club indy tracks, the MENG Indy track, and the Orochi kit tracks.
Finally, I made the front idler mounts so they would be oriented correctly, fill the motorization holes, and have better detail.