Is there a GRF for changing the start year of road vehicles?

[AndersI]

I've made a set of Swedish trains (not finished, see my other thread), that starts from 1920, but playing my Swedish scenario I find that some road vehicles are sorely needed at the same time.

Is there a GRF just for changing the availability year of the standard road vehicles? Or a more realistic one, changing the availability year AND lowering the speed and capacity? No need for new graphics, just stats for better game play.

How difficult is it to make one? I'm using GRFMaker, not NFO directly.

[DaleStan]

Not hard. Set prop 00 or 1F for each vehicle, and no other properties.

Actually, you can probably get away with setting prop 0E too, if GRFMaker won't let you leave that unset, at least as long as you don't add an action 3.

[AndersI]

Thanks! Works as expected (at a quick test). Attached for anyone else interested. Please inform me of any problems.

[Wile E. Coyote]

You can offer this GRF to TTO set. In that case also will be good to change introducing year for all wagons.