The Advance Adapters Atlas Adapter Spacer (SKU AS-0404) solves the same fitment problem as the 3/4" version in this line, but at a 1" spacing — needed on Atlas conversions where the transmission's output shaft "stick-out" is longer relative to the rear tailhousing or adapter, causing the shaft to bottom out during install.
Trimming the output shaft down is the usual fix, but it isn't always the right call — some transmissions don't have enough splines on the main shaft to allow for trimming, and on others you may simply not want to modify the shaft. This spacer adds the needed 1" of clearance without touching the output shaft itself.
What's included:
- Adapter, 4L60 to D300 Spacer (51-0404)
- Bolt, 3/8-16 x 1.00" SHCS Zinc (723731)
Sizing note: this is the 1" spacer, built for the 4L60-to-D300 application specifically — for a 3/4" spacing need, that's the AS-8603 spacer instead.