The closest Soviet equivalent to a Jeep, or a Humvee? There's not necessarliy a straight one-to-one mapping.
If you're looking for a "Soviet" jeep equivalent, Military Wheels produces a number of kits of the UAZ-469. This is technically Ukrainian now, but was in production before the split of the Soviet union. It's the descendant of the GAZ-69, which was the replacement for the GAZ-67 which was basically the WWII-era Soviet jeep. Military Wheels has produced at least a couple of different variations on their kit - Ukrainian SFOR jeep, version with a recoilless rifle, etc. The basic vehicle was also copied by the Chinese and (with a different engine) produced as the BJ-212 - Trumpeter makes/made a kit of this fitted with a recoilless rifle.
However, if you you're looking for something that's a closer equivalent in concept to the Humvee, the GAZ-3937 "Vodnik" is what you're after. At the moment the only kit I know of in 1/35th is an all-resin kit from Navigator which used to be available from Modelpoint US. Not sure if they still have it. Unlike the Humvee, where there's a basic common cab and the back-end of the vehicle is modular (well, sorta), both front and back are modular. The front's got a number of different passenger layouts, and both full-width and half-width cab driver's cabs, the back can be anything from an ambulance to troop seating to a unit mounting the same turret as the BTR-80.
It's a cool vehicle - it'd be nice to see some manufacturer give a try at a few variants. However, as of now, the Navigator resin kit is all there is.
Hope this helps.
Al