I picked up my truck yesterday and was wondering what is the year of manufacture of the engine. All I had on the engine was these numbers 4728/9456/2

 

There is alot of what seems to be alot of different answers to your question. Mine is a big 5in by 3 in White sticker with blue writing on the valve cover on the passenger side of the truck. Mine has the build date like 10/03 and has the VIN # and all the stats on the engine like 325Horse at 3300RPM 560LB Torque at 2200RPM all that good stuff. Some people say that they have it on the driver side valve cover. mine is on the passenger side... so take a look it shouldnt be to hard to seee if its in the same spot as mine. Maybe have to get up on the tire to see. Dont know im only 5'8'' so...

 

still cant find it, all I have is the white and orange sticker on the passenger side valve cover with the horsepower and torque ftlb listed and on the right side drive valve cover is a white sticker and its has 4728/9456/2

 

never mind, I called my service guy at the place I bought it and he told my truck does not have it stickered from the factory with the date on it. the vin number will list it, he told my trucks PSD was made 5-10-04

 

See here for what the engine sticker looks like:
http://www.backglass.org/duncan/ps60...l/ps60_008.jpg
It is found on the FICM which is on the driver side valve cover back toward the firewall.