The Sheridan is a regular model we stock. Our store is just closed right now, as half our crew on vacation, as we're sorting out our inventory with a new shipping partner. WCP or Brigade may have a few in stock.
For the Mutt's we don't have one...but the ones Ian Crouch did do come with the TOW setup. I think Sloppy Jalopy will be casting those soon.
I'm finishing off a few more WW2 variants and new master models the next few weeks. I'll get right into the moderns starting with the BTR-152 and some others as soon as the WW2 stuff goes out to casting.