PDF of manual to modify original XLerator to support 2MB and 4MB SIMMs (stock 16MHz XLerator supports up to 1MB SIMMs) circa 1994
"When used with appropriate software, this XLerator modification will allow your XLerator to use one or two pairs of 2MB and/or 4MB 30 pin SIMMs"
Very few of these in the wild.
(2022-05-27 Re-uploaded with formatting/page size corrected)