Zoey71

Looking for options. I ordered a GM TrueTrac 8.5" 10 Bolt rear end Kit. 30 spline 3.73 gear ratio to a do a swap in my 2006 Silverado Z71. (The current gear ratio is currently 3.42.) initially I thought the transmission ( 4l60E) went out due to no drive/ no reverse. I order a rebuild kit from Probuilt Automatics. Then order the TrueTrac kit to replace the rear end as long as the Trany would be upgraded. The Trani was rebuilt and reinstalled. Then the motor would not start, it would turn over but not start. So knowing I had to get a tune update for the gear swap I asked my guys to complete the mechanical work before going to a tune specialist. After trying to install the Worm Gear and pinion my mechanics told me that the race bearings inside diameter fit, but the outside diameter was too small on the replacement kit. They showed me how destroyed the current spider gears are after removing the hub cover to do the swap, so it has to be replaced anyway just not a performance upgrade issue.
1. Could the worm gear disintegration lead to no drive/ no reverse in the first place?
2. Is it possible to acquire different races than the Kit provides, possibly with a bigger outside diameter?
3. Or should I just take the entire rear end out and take it a rear end specialist and eat the cost?
4. I believe I ordered the wrong bearing size 8.5 instead of 8.6 according to to the my recent search, is there a bearing conversion kit available? (the description prior to ordering the kit did state 8.5/8.6)

The trucks motor was recently upgraded. 5.3 L33 -
Pro LS forged dome pistons and rods.
5 angle valve job,
bored 10 over.
BTR stage 2 low lift truck cam. 212/218,
SCP Rockers,
BTR LS 6 valve springs
TBSS intake manifold,
799 heads competition ported and polished,
headers, x-pipe dual exhaust.
(goal was 400 whp)
The truck was also recently tuned.