I would say that this minor variation in oil viscosity won't negatively effect how the bushing absorbs oil.
And, just as a semi-related heads-up for you WSM (and any other new NV3550 users), make sure that your rear driveshaft is in good shape and that your pinion angle is correct before you go for a drive.
I say this in case you're doing suspension or other driveline work while you're doing the trans install.
With the "looser" nature of the NV 5-speed, a driveline vibration can manifest itself as an extremely noisy gear box. And I mean, EXTREMELY. As in, it must be defective so it should be replaced noisy.
Evidently the torsional vibrations will transmit themselves quite effectively through the trransfer case and into the trans, and sound just like what an old worn out and loose countershaft/idler shaft issue would be.
Similar sounds can be heard in ancient truck 4-speeds that are in need of a rebuild.
Tighter tolerances in a car-type trans, like our original 3-speeds, don't show the same characteristics and the vibrations usually only show themselves in the normal manner.
Just mentioning it here, as you're about to install the NV for the first time and wanted you to be aware. The NV's are going to be slightly noisier by nature than the old 303 Ford tranny anyway. If your floor is closed and insulated, you'd never know it. But if your first drive involves open floor panels and no shifter boots, you're likely going to hear some crazy stuff coming out of the tunnel!
Paul
