If it has aluminiun planitaries in it, the splines on it wont last too long. I've broke every piece of the drive line in mine.(since the new converter)
I will also say if you have a converter that slips a lot it will help the trans live..

69 340 swinger streetcar 8.13 1/8th w/1.90 60ft w/ 3.55s 69 422W9 Dart stock suspension,5.27 on 275/60s,single bar plate