Serial Number R5222 was built in September 1963, well into the 1964 model year. What you are giving as body numbers appear to be Serial Numbers (body numbers are different). P still indicates a regular 289 and R and JT still indicate an R1 depending on if it was initially installed in an Avanti or Lark type or Hawk (RS and JTS for R2). Today, some 46 years later, the K-code 'Hi-Po' Mustang is still one of the most sought after classic Mustangs. 1964s have date code numbers and there can be multiples of the same number. 65 289 Holley 4160, F4B, Dougs Tri-Y Headers, 3. 1963s have sequential, individual numbers. Ted - Studebaker changed their engine numbering from the 1963 model year to the 1964 model year. What I need to know is this an anomaly, or did Studebaker indicate Avanti engines with something other than R, R2 and so on. It has been opened up and worked on by someone and converted to a standard 289. The engine number on 5222 turned out to be a standard 289 as indicated by the heads and the camshaft. The car I am questioning has a build date of 8/30/63 with a body number of R5222. The build sheet on my car dated 1/30/63 with body number 63R3339. It is my rather limited understanding, The R1 engine was labeled with an R and the number, R2 with RS and the number as it is shown on my build sheet. Usually, but not always.This question is from someone who has built Studebaker engines for several years, but has recently purchased and Avanti and have attracted several others to ask questions and have work done on vehicles that are rather new to me. And even if the block has a 302 cast in it doesn't mean that is what Ford made with it. However, the heads won't tell you whether its a 289 or 302. One of my intake manifolds has the cylinder numbers swapped incorrectly: 1, 3, 2, 4 as I recall. What look like screw heads at the ends of many of those numbers were just screws holding the digits in place. It was sort of an erector set where you put the correct letter/number in the slots in the mold with nothing to prevent getting it wrong. (Im not going to post the skew rate (the rate at which the engine number deviates from the Jeeps serial number) at this time because that information is still being assembled and I dont want to 'taint' any current research by posting premature numbers. And they didn't always get the casting marks correct. The engine number should be within a few hundred of your serial number of 41XXX. Ford changed exactly what numbers and letters were cast fairly often. Other times that spot had just the last letter of the part number for the head which would not be a T (last letters didn't normally go that high). The other one I think is a date code of 0G18: 18 July 1970? They often cast a year where yours has a T, i.e. Exactly what it means is not entirely understood. The numbers in a circle are some kind of a foundry stamp telling something like when that part was cast.

289 engine serial number