Plastic Soldier Comp. is around with two reliable kits of a fast-building Sd.Kfz. 251.
These kits/sets offer the most common sub-versions of the 251 half-track, a flame version, the "Stummel", etc..
Not gettable from PSC is the 251/22, a late-war 7.5mm PaK-upgrade of the half-track. Never mind! Over the years I stored a quite nice 7.5mm PaK 40 from Comp. Roden in the spare box. And ... this gun fits just perfectly into the half-track.
My rendition of the 251/22 is getting in a ready stage. Looks quite convincing to me. Again PSC made a good job.