Aligning a new front cross member & dumb irons

Evening all,
I'm contemplating replacing my front cross member & dumb irons in one piece, the engine is bolted in to the chassis.
Will the engine provide enough of a brace to stop the chassis springing out or twisting once I make the cuts?
Also, if I ensure the back tub is level both ways and level the new section would that suffice?
ATB
Dave

I’d still bang a brace bar of box section in behind it before you chop if I were doing it. And make datum points and take measurements

The big problem is welding it on in the wrong place. If it startes to shift during welding you will never get it back. Measure everything, and tack and measure again. Can you use a laser level on it? The front spring hangers are key, same hieght and same distance. I think one of the benfits of doing this yourself is that you have time to check and re-check. Met a guy who'd paid and "expert" to weld on a rear 1/4 chassis and it was on wrong. Got half his money back but the vehicle is lopsided and always will be until the whole lot is cut off.

Weld lumps of box all over it and weld the sod to the floor anorl for good measure.

The whole dumb iron ends rotted off with the ends left bolted to the ends of the leaf springs, I'm ordering a front end from Craddocks and was intending cutting directly across the rear of the cross member. Can I reasonably assume the distance will be correct from the rear of the cross member forwards to the bolt centres - there isn't really any specific datums other than the flat top of the assembly and the hole centre for the swing link?

Also, how come there is a large price difference between chassis suppliers - thinner material or inaccurate dimensions?

Thanks again in advance guys
Dave

Is the rest of the chassis relatively rust free? It would seem a shame to go through the expense and effort of fitting a new section only to find the rest needs replacing in a year or two.

Col

Re alignment - you should be thinking about putting rods through the spring shackle bushes in the chassis and getting these parralell and square to the new dumb irons. If this is out the wheel aligments will always be out.
Re price, I can't speak for chassis, but for outriggers I've found the cheaper to be fine and as good as the more expensive. I doubt there's much difference in metal thickness, there could be differences in metal specification but without test results its hard to know. There could be differences in the number of extra brakets and what's included and what's extra.