A quick look at the R/C Truck I designed and created from scratch.
Here is a link to all of the files:

https://drive.google.com/folderview?id=0B7mhAguM086SZDJLN0stcXFSVDQ&resourcekey=0-BqQXE0oTi5LoXl9exz7QLw

Here is the link for the motor/gear box. It's considerably more for them now though(I paid $13 for 6pcs.), but you can modify something else. A lot of parts are just hand filed metal shafts I had lying around.
https://www.ebay.com/itm/DC-3v-5v-Worm-Gear-Motor-Variable-Speed-Gearmotor-micro-reduction-gear-box/121230293476?hash=item1c39e379e4:g:ZBcAAMXQfvlSoCY8

Here is a different link to a motor that somebody may be able to make work.
https://www.ebay.com/itm/DC-3V-5V-100-160RPM-Mini-Precision-Turbo-Worm-Gear-Motor-Speed-Reduction-DIY-Toy/123177459179?hash=item1cadf2ddeb:g:I4EAAOSwzqBcsEuz

I also found these motor which might work better if you can't find the ones listed above.
https://www.amazon.com/dp/B01N9MS3UZ?psc=1&pf_rd_p=5d452ff1-f5f3-4a40-8eb4-3cd6ad7d750c&pf_rd_r=MZHGGE7ZHCBFB2EAEEDD&pd_rd_wg=jfE45&pd_rd_i=B01N9MS3UZ&pd_rd_w=8WG6l&pd_rd_r=9a73dee7-2f1f-47c6-9555-0ec174f23606&ref_=pd_luc_rh_crh_rh_bxgy_04_02_t_img_lh

Front drive system information here: 
https://www.youtube.com/watch?v=OjAJVNdX5xs