BH wrote:
Jim,

The information in the Sept. 1954 Counselor was later rescinded for 24th, 25th and 26th Series cars in the Oct. 1954 issue, but was mainly concerned with transfer of flywheel and related parts for replacement engines that were built up for Ultramatic.

However, you're getting warmer. The issue you need to look at is from December 1951 (SC Vol. 25, No. 14). This is where it was first announced that the service engines would be built with hydraulic lifters, including the 288 (with oil filter then required).

Yet, take note of the paragraph reminding the reader to:

Quote:

Be sure when stamping the engine number to add the suffix letter 'H' after the engine serial number.

This suggests that the service engines not only came from the factory un-numbered, but that the dealer should stamp them. My gut feeling is that this was to permit application of the vehicle's original motor number to the replacement; the 'H' suffix may have been a visual cue to identify a replacement unit, as well as presence of hydraulic tappet equipment. I can imagine that step being skipped by a lot of installers, though.

I've edited the relevant Service Index entires to make these distinctions a bit more apparent.