If you could mate I'd appreciate it. Picture speaks a thousand words n all that! I think I understand though. Oversize my holes to accommodate a weld to hold tubes in place. This would mean that the tubes are welded in place from the outside visible edge? The inside (tank side) of the rail should hopefully hold them in place too if secured both sides?Bit of CAD (cardboard assisted design) will help here, take card big enough to cover all rot being cut out, cut as a template, wallop bolts through to mark holes and use a hole punch to make them oversize to accommodate the crush tubes, I like a 1 to 1.5mm gap all round the tube to ensure perfect welding in of the tubes, cut the rot out and grind round the tubes to clean them back or buy some new tube and fit new, it's up to you, geometry is not affected so you can be a half inch out without worry.
If you want I will try to explain with pics when I gets home tonight.
What is the chassis rail like under them caps? Bet its shot to bits too
I cant really tell how bad she is under them. I think this truck was an beach dwelling series in its former life lol