E40D Trans Help ?

[FordPower460]

Hello  i have a 1990 f350 crew cab with a 460 4x4 with e40d trans       i would like to know more about these trans    " are they hard to rebuild? "   i dont have forward   but i have reverse all day.   if i put it in 1st "low" and rev at 1800 rpms for about 20 seconds the truck wll roll but only a couple mph   2 and drive it just revs up and wont move     i would like any info i could get bout these transmissions    idk if its the clutches or the front pump ?     Thanks

[J.C.]

check fluid level?

[4x4xdodgeman]

its not the pump. the pumps do not go out. in your year of trans has some up date parts. when go though the trans buy all electrical parts, i have none a few people to cut that corner and  have to go back in the trans.