my drivetrain shakes a lot in 1st and 2nd.. help?

[dreamer]

so i just swapped out a ka24e automatic and dropped in a ka24de 5spd... and when i drive it in 1st and 2nd gear, in the low rpm range (i dont know exactly because my tach doesnt work) the shifter shakes slightly, then more and more violently... and then i hear/feel some thing bumping against the underside of the car... i'm assuming its the transmission or driveshaft or something of the like.

anyone know what it could be? i dont think its a tranny mount and i think my driveshaft should be balanced... but what could possibly cause this?

also, my tach doesnt work. anyone ever had a tach stop working on them? i swapped in a DOHC gauge cluster with the motor.. first time i started it, the tach jumped from 0 to 1500......... then never moved again lol