Older Housings And Carrier Interchange Question

[Flynpenguin]

My 55 LT has the rear end housings which use 6each 1/2" bolts positioned fore and aft, 2each 3/4" bolts on the right side, and 2each 3/4" through bolts on the left side. The rear housing is stamped 1QFA5272AP6, and SWD 52. I have a set of drop ins from an early B model stamped CRD93-15-39, which uses 10each 5/8" bolts. My existing drop ins are 8.31, and I'd like to use the B model drop ins since they are 5.03. The LT has good straight housings with very good brakes and light springs, and the B model brakes are junk, the springs are much heavier, and the front housing is pranged, is it possible to ream the holes on the B model drop ins to 3/4 so they can be installed in the LT housings?

[mackaholic]

My 55 LT has the rear end housings which use 6each 1/2" bolts positioned fore and aft, 2each 3/4" bolts on the right side, and 2each 3/4" through bolts on the left side. The rear housing is stamped 1QFA5272AP6, and SWD 52. I have a set of drop ins from an early B model stamped CRD93-15-39, which uses 10each 5/8" bolts. My existing drop ins are 8.31, and I'd like to use the B model drop ins since they are 5.03. The LT has good straight housings with very good brakes and light springs, and the B model brakes are junk, the springs are much heavier, and the front housing is pranged, is it possible to ream the holes on the B model drop ins to 3/4 so they can be installed in the LT housings?

Nice looking LT, always good to see another Mack in CA.

As for the drop ins, they should fit fine. Most of the locating takes place at the flange and on the ears at the bottom of the carrier, not with the holes so drilling them out shouldn't be a problem. I have even seen the later drop ins with 18? bolts used in the earlier housings. The only tough area is the through bolts. The later drop ins used bolts under the side cover instead of the long studs. If I remember correctly you have to tap the upper holes housing and put in larger bolts under the side covers and dummy bolts with nuts in the lower holes.

[fifth wheel]

On the left side run the bolts from the bottom up with a copper washer on each end. Use a locknut and seal the threads so you don't lose the oil out of the pinion housing.

FW

[Flynpenguin]

Thanks. It's been a long time since I last pulled some drop ins and I'd forgotten about the flange and inside ears. As soon as I finish fitting the new hood and send it to the painter, I'll move to the back end and start on the rear ends.

[Lmackattack]

nice looking truck...Fyi...there is a guy down in Galt Ca that has some old mack Parts. if you need a local source for parts PM me and I will give you his info