Hold on a second Rama777!
Your axle beams or square tubes were bowed the day they were installed way back in 1971. I think you are speaking of the axle beams (between the frame rails) since you spoke of the frame spacing. This is the way that TOE IN is controlled after the trailer plus it's load is put on top of it.
Now, it IS possible you need new axles (looking at the age of your trailer) but there is a completely different way of ascertaining that.
Look up the forums section on axles, and you can read non stop for days.
2000 390 Landyacht XL
1989 29' Excella
WBCCI #6673 jerry Hodge
Have no intention of arriving at the grave safely, but rather to skid in sideways, chocolate in one hand,throttle in the other, totally worn out and screaming
"WOO HOO, WHAT A RIDE!"