got to pull the box out of my 85 vette is it a big job, it is a 7 speed

Not if you have basic mech tools and a floor jack.Hoist helps
If no hoist, need to get car up on tall jack stands to have working room underneath
Support trans , remove drive shaft and C beam to diff . Disconnect wiring and shifter linkages at side cover .Support engine , unbolt trans and slide out.
If you want to remove bellhousing need to lower rear of engine to access to top bellhousing bolts
Watch dist to firewall and engine to wiper motor clearance when lowering engine

got to pull the box out of my 85 vette is it a big job, it is a 7 speed

Oh, including R makes it a 7 speed, gotcha! good luck with that job!

I would get some jacks and an extra set of hands would be very helpful!

Oh, including R makes it a 7 speed, gotcha!
No .; it is not a ZF6

It is a factory fitted DNE 4+3
4 gears plus 3 O/d gears = 7

Get the car up on stands and it's not that bad of a job....Really.

Get a trans jack or some way to lower the gear box once disconnected

Most importantly, don't forget the ground from the head to the block. MAKE SURE that goes back on.