These rat walkers from Vinci miniatures are part of their fantasy ratmen army but also work well with their Mechrat army from their Dark Future range.

All the parts are interchangeable.

There are 3 different riders (each with two sets of arms)
3 different nose pieces (Nose piece one also has three different windscreen pieces, or you can leave it off to mount a gun there)
3 different engine pieces
4 different rear/tail pieces
6 different pairs of legs
9 different weapons

By default a random complete model will be supplied, as there are simply too many options to specify with dropdown list.
If you would like specific parts, please contact me to discuss this.