'74 K5 Cheyenne with a swapped-in 454. Has T350 auto and what I've found out now to be an NP203. Truck has 4-inch RC lift and the front has been converted to locking hubs. Little disappointed to find out about the 203, but this will be a mostly street rig on 35s and open diffs. I'm getting a lot of gear oil blowback somewhere beneath the truck and am trying to track it down. Both diffs are drained and I'm rebuilding the vents. The case does not appear to have a vent tube. The 203 runs gear oil, correct? Next, there are two crossmembers connected by a skid plate. Is this normal? The rear crossmember doesn't appear to actually support anything, other than the rear of the skid. And both crossmembers have been dropped, assuming to compensate for angles from the lift. Is this necessary? I'm used to Jeeps and Toys and don't have a clear understanding of how this system works. I'll attach a photo of what I'm talking about: For street use, will the 203 be acceptable?