Product Review ’71 GMC Grain Truck Cab with Step Tanks

Another product review of a Rockin H product by Tony Dixon. This project started out several months ago. I have wanted my “grandpa’s” grain truck for a long time. I spent many summers taking wheat back and forth to the elevator in Russell and Ellis County Kansas in that truck and I had to have one. If you recall the first version came back from the artist too small. HO scale actually, so back to the drawing board with explicit instructions from me.

Tony had been giving me pointers on this truck as I posted updates on Facebook. He seemed to know what he was talking about so I asked him to do a review on this cab and a couple other products associated with this build. Full disclosure, I gave Tony all the parts for free in exchange for this review. Actually, I’ve not even seen this cab in real life myself yet. Only pictures. Look for a review on more 3D printed parts in the future.

Review of the 71 GM Cab with Step Tanks

Upon opening the packaging my initial response was that they components were very nice that come in the frosted detail plastic from shapeways, on further inspection I found a few issues but i will go into them as the review goes on.
I size compared the cab with other available 1/64 scale 67-72 bodied vehicles, they were:

  • Greenlight 67-72 C-10
  • Hotwheels 67-72 k5 blazer, shortbox fleetside, and shortbox stepside
  • Johnny Lightning 69 k5

My hopes were to find a suitable donor for a wind shield being as the real c60/70 share the main cab, doors, dash and glass with the C/K series of the same vintage, but although I found the cab to scale out nicely with these trucks it is extremely boxy compared to them and the real cabs which rendered the glass from any of these useless on the build.

Next I started cross referencing the cab with available chassis options. To my joy the cab will work well with bare DCP Peterbilt 379/389, Kenworth W900L and K100, and International Transtar COE chassis with little to no modification necessary to either pieces. The cab will also work on the M2 Machines medium duty (Chevy, Ford, Dodge,or Fargo) chassis with lots of work to either the chassis or cab.
The issues I found upon initial inspection of the component pieces were

  • the cab roof is extremely square compared to the real truck and others of the same scale and vintage style.
  • the steering wheel which is printed into the cab is under sized and more suitable for a “lowrider” than a medium duty truck.
  • the center “jump seat” printed on the floorpan extends too far in front of the other 2 seats and blocks the installation of a floor shifter similar to the 1;1
  • the step tanks are a little on the small side compared to the ones used on the 1:1’s locally
  • the “Chevrolet” grill is not accurate
  • lack of much interior detail (no concern to me but some people may not like this)

On the positive side the cab is equipped with the optional large rear window option for the 1:1 GM medium duty trucks. When ordering you have the options of tanks or running boards for under the doors and GMC or Chevrolet grills. Having thes
options available will help greatly in replicating the real trucks.

Even though the Chevorlet grill was in-accurate the detail on both it and the GMC grills are outstanding and I hope to see the proper Chevrolet grill in the near future.
Before priming the components I reworked some of the minor issues. To fix the steering wheel issue I first removed the printed steering wheel and column using a X-acto knife. With a #72 bit in my pin vice I eyeball drilled a hole from the bottom of the cabs “firewall”, through the steering column area of the “dash”. After drilling I assembled a new column using a Tractor Fab 3 spoke steering wheel, a strait pin and a small piece of brass tubing. Once the new column was complete I inserted the strait pin into the hole. I drilled to install the column into the cab and secured it with a small amount of CA glue (super glue).

Next I moved onto the oversized jumpseat which I cut down using a cutoff wheel on my Dremel tool carefully cutting flush with the floor and flush with the leading edge of the seats. Cnce the excess of the jumpseat was removed I drilled a #72 hole approximately centered right to left in the cab and between the now cut down jumpseat and the front of the floorpan. This hole was to install a shifter for a manual transmission which I made from another strait pin.

Once these modifications were complete I utilized the same paint prep procedure that I outlined in the MA-18 bed review then primed all parts with Duplicolor sandable automotive primer. After the primer was allowed to dry I painted the cab GM Fathom Green Metallic using Duplicolor color match paint and the interior section and tanks were painted gloss black with Rustolium high gloss industrial paint. As for the detail painting which was done after the primary paint had a day to dry I used Testors Model Masters Acrylic paints in chrome silver, flat black, gloss black, and insignia red which I hand applied with a fine brush.

For a windshield and rear window I used clear styrene that I cut to fit and bent accordingly (this took multiple times to render a useable part) which I installed with a minimal amount of Testors liquid glue for plastic models. When paint was complete and windshield installed I finished assembly by installing the cab onto a junkyard chassis I built using the front half of a DCP Kenworth W900L chassis and the rear of a DCP International Transtar chassis connected with brass channel to make the chassis the length I needed for the build yet obtaining the leaf sprung rear that the real C series medium duty trucks had of this vintage.

Overall I give this kit:
8/10 for appearance
6/10 for accuracy
7/10 on ease of assembly (mainly because of modifications made to components to increase accuracy)
8/10 overall

Even with the issues I feel this would make a good addition for anyone looking to add a older GM C-60/70 to their collection or model farm and would recommend it in those cases, I however hope that sometime in the future that the issues are addressed and corrected especially in the case of the Chevrolet grill and cab roof.

 Parts out of the package  Compared M2 Dodge  Compared to Greenlight Chevy  Printed Steering column
 Aftermarket steering column Altered interior GMC Grill Chevy Grill
 Cab on DCP Frame Cab on M2 Frame Final assembly Setting on the farm


  1. Tony on April 9, 2014 at 8:15 pm

    Thanks for the opertunitys I can’t wait for the revisions.

  2. Kal on April 11, 2015 at 2:53 pm

    Hi wow cool old 67 GMC C960 well up here in Canada the Canadian model numbers were 900’s we have a old 67 at the farm same color green it is 2 1/2 ton 950 V8 327 Muncie SM 420 w/ 14x8x5 wooden grain box that is still so cool that you made those old style GMC cabs our other grain truck is a 77 GMC 6500 model with the 16x8x4.5 grain box 🙂 so cool

    • Eric Haselhorst on April 12, 2015 at 10:52 pm

      Thanks. My grandpa had 71 GMC I used to ride in as a kid and I always wanted a model of it. Thanks to 3D printing I got one. Now I need to make a bed and get this bad boy finished.

      Thanks for the comment,