Firestorm

okay, so for the life of me, i cant find any info on this.

here's my situation. i had a 180sx manual without abs, crashed it and now i want to swap the engine into a new chassis which happens to be an AT with ABS.

now heres where i'm stumped. i guess i could build a driveshaft of the right length if i combine the AT/ABS rear half of the shaft with the MT/non-ABS front half.

what i'm worried about is if it needs to be balanced as a whole or if the halves themselves are balanced already, so i could just bolt the two halves together and call it a day?