will gearbox fit & what is the best gearbox

[excavator81]

hi all builders just wondered if i ordered the chassis with mt75 tunnel but could not source one at time of build would i still be able to fit the type 9 box in would it be a case of fabricating bigger / longer gearbox mounts has any one done this before im sure it would not be to much trouble?????.....

ALSO
what is the better gearbox type 9 or mt75 any info would be great many thanks DAN ...