I'm gonna resurrect this year-old thread and add to the mystery even more. During the process of reassembling my LT5, I have come across even more stamped dates. It seems that pretty much every major component has a date stamped on it.
I don't know what the typical date range for all the parts on the engine is. Should they all be within a month? 3 months? More? On mine, the earliest dated part I found is 9/20/89 all the way to the date on the girdle which is 3/8/90. That is an almost 6-month span which seems excessive to me. And the car wasn't even assembled until 5/22/90 which is the "PRICED" date on the original invoice that I have.
I've posted a list & pictures below of all the stamped dates I've found and what part they are on. Some of the dates have a letter after them.
Crankshaft main
bearing cap girdle ------------ 3/8/90
Engine block ----------------- 3/7/90 B
Oil pan ---------------------- 1/8/90 C
Secondary actuators --------- 1/8/90
Plenum ---------------------- 1/5/90 A
Crankcase
breather cover --------------- 12/22/89
Oil pan
suction tube ----------------- 9/20/89 B
Both cylinder heads also have a cast-in number "89" which could indicate the year, but I'm not sure.
Pictures:
Engine block & girdle dates.
There is also some free-hand engraving in the "V" area of the block under the starter with a date (matches the stamped date). I colored in the engraving with a sharpe to make it more visible.
Oil pan date, it's on the front, passenger side edge of the lower surface of the oil pan.
Secondary actuators date, which is the same date as on the oil pan.
Plenum date, this is on the bottom just behind the DIS module.
Crankcase breather cover date.
