Well it is just under 75mm as forcing tr1 and tr2 to join ff4 caused it to push ff4 back abit, but this should be fixed by shortening ff2 and 3( i desperately hope) anyway, its about 3-4mm or less pushed behindso around 72mm.
(wow, ive never worked to these tolerences before as normally if i weld somthing slightly off, i just change my design and say it was intentional and that i welded everything right
)