They look to be from a Hartland Tram. Not entirely sure what the running would be like as the wheels have a quite course surface to them so track pickup on just one bogie may be a bit iffy.
JonD
They're from the Hartland Bogie interurban.and it's MoW linecar cousin. I think one was also used in a reproduction of a Delton railbus that HLW and Aristo co-operated on but I wouldn't swear to that. They pick up on all four wheels and generally run fine - even on their own - on plain track, but once you get to pointwork etc, they suffer from the same problem as every other short wheelbase G-scale mech, and can get themselves isolated on things like point frogs or similarly sized bits of corrosion. So if you don't actually need two to haul the train, I'd generally recommend fitting additional pickups to the trailing bogie/vehicle if possible. Both the interurban and linecar have one powered and one trailing truck.
The wheel surface is cast, and not as fine as say the machined one on the (now discontinued) USA 44t block, but unless you're a scale size passenger taking a ride I honestly doubt you'd notice the difference compared to rail joints and cornering forces on R1 at a scale 30mph...
They're also very easy to fit - just arrange a portion of the floor at the appropriate height, whack a 3/8" (9.5mm) hole through it where you want the pivot, plug in the block from underneath and fix with the palnut on top.
Jonathan
g-bits