Narrow Gauge Truck Size

I have often wondered why the seemingly arbitrary wheelbase of of narrow gauge trucks.

I can imagine that the longer the wheelbase, the more stable the ride, i.e. passenger trucks.

The shorter the wheelbase, the better able the car is to deal with sharp curves, i.e. the 3'7" archbar trucks found under so many of the Rio Grande's freight cars.

Why 3'7"? Why do the longer freight cars have longer wheelbase freight trucks? More stability needed for the longer underframe?

Was there a rhyme or reason for the selection of the length of the trucks? I can understand the upgrade to Andrews or Bettendorfs with the introduction of steel underframes. I can also understand the retention of archbar trucks for the majority of the rolling stock fleet, given the desire to be rid of the narrow gauge and the cost that would be involved with upgrading the trucks of the wooden rolling stock fleet.

Why did other narrow gauge railroads use different wheelbase lengths for their trucks than the Rio Grande when these narrow gauge railroads had essentially the same length, or less, of rolling stock.

Finally, was it possible to mismatch the truck types and wheelbase lengths? I would imagine that modifications to the brake rigging would be necessary, but hardly beyound the capability of the mechanics who maintained the equipment.