Help with L series gearboxes please

[Subardoo]

Hi im trying to find a L series high low range box with front diff ratio 3.9 out of the early 1985 86 cars but cant find any i have a later 3.7 ratio high low range out of a later model and wondering if anyone could point me in the direction of aomeone who might be able to make 1 gear box out of both my single range 3.9 gearbox and the high low ratio 3.7 gearbox thanks.