drube,

I did an upgrade to my H9 AT6 landing gear to 3/16" wire. I called Robart and got the wire that was already bent for an AT6 for $12. They were very helpful..........call Robart and see if they have wires for the P51.....if so you will have no problems, they were the right length for my model and only required very carefully enlarging the holes for a press fit of the new wires. This is a common mod on the AT6 and maybe it can be for your P51.

Andy