Can an early ('98) 4L60E with the shallow bellhousing work behind an LS?

Check the exact unit before planning on it. What our sources say:

• Speedway: 1993–97 4L60Es have a one-piece case like a 700R4. A two-piece case (separate bellhousing) arrived in 1996. In 2000 the bellhousing gained a bolt hole at 12 o'clock and got 3/4 in deeper to fit a different input shaft and converter.
• Wikipedia: from 1998, 4L60Es paired with Gen III small blocks got a 300 mm converter, input shaft and pump; non-LS units use 298 mm.

Sources differ on the exact year, but the point is the same: LS-spec 4L60Es use a different input shaft and converter. A shallow-bell early unit isn't a drop-in behind an LS. The simple route is an LS-version 4L60E (or its bellhousing, input shaft and converter). See will a 4L60E bolt up to a 5.3 or 6.0.