The first part of the code should be a date year and should have a letter in front of the 4TE, D4TE which would date the block as a 1974. The next two letters TE normally tell what it came out of. Exapmle T = Truck, E = Engine. The 6015 normally designates the part number that identifies the part, in this case it should be Engine if your number is correct. The rest may indicate design changes, as my books don't show any exact match for that set of letters and numbers. There are some web sites that you can go to and spend hours searching through for an exact match but I don't have them listed. I am sure some of the other people will chime in and point you to someof the sites. Good Luck.
Ron
