In 1942, the Russian military engineers were urgently searching for suitable BM-13-16 "Katiusha" rocket launcher chassis as addition to and substitution for their own, by now more and more obsolete ZIS-6 truck.
Therefore, in the course of this year, they tested and deployed no less than 9 Lend-Lease truck chassis, partially presented here, among them the Dodge T-203-B (Source: Sergeyev, p.24).
Primarily, they were concerned about the truck's frame stability and passability on poor ground.
At the end of the tests, they had found the best suited chassis for the rest of the war and they called it BM-13N, the "N" for "normalized".
It was, you already guessed it, the Studebaker US6.

Note
The vehicles is shown with the windshield protection shut, the rear ground stabilizers installed and with the sixteen 132mm rockets loaded.
In other words... it's ready to fire!