Year and model shown as prefix to engine number. For example 8-T-33445 is a 1938 Speed Twin (later identified as “5T” instead of just “T”). Frame prefixes were-”TH” for early Speed Twin. “TF” for the T-I00 and later 39/40 Speed Twin.

Year shown in engine number prefix with two figures. For example 40-5T-26445 is a 1940 Speed Twin. This practice followed religiously and some single prefixes may appear on postwar models. Frame prefixes were ‘TL” for the 3T up to 1948 and TC for 1949. TR5 for 1949 was followed by a ‘T” after the actual number. All other frames were TF. TR5 models did not have separate number series but ran concurrently with all other models. I.E. 112671 was last ’49 TR5 and I1 3386 the last ’49 5T.

Note: All Grand Prix T-1 00′s have letter ‘R” suffix following engine and frame numbers. TR5 models had separate number series; engines from 101001 to 106424, frames from TC11001-T to TC13107-T. By 1950 frame and engine numbers were matching.

Thanks to Dave Gaylin and Lindsay Brooke for printing the above information in their book “Triumph in America”.

1940 to 1949 Models

SEASON ENGINE NUMBERS FRAME NUMBERS
1946 from 72000 prefixed as before
1947 from 79046 prefixed as before
1948 88864 – 102235 TFI 5001 – TF2500
1949 102236 – 113386 TF25001 – TF33615

Military – TRW Military 500cc Side-Valve Twins

YEAR ENGINE NUMBERS
1950 14401N-14459N
1951 6044NA – 1432ONA
1952 22001NA – 22838NA
1953 22839NA – 23273NA
1954 23274NA – 23322NA
1955 23323NA – 23597NA
1956 23598NA – 25447NA
1957 25448NA – 27127MA
1958 27128NA – 27175NA
1959 27176NA – 27346NA
1960 27347NA – 27645NA
1961 27646NA – 28185NA
1962 28186NA – 28464NA
1963 28465NA – 28827NA
1964 28828NA – 29605NA

1950 to Current engine and frame numbers match

DATE T15/20 UNIT 350/500 PRE-UNIT 500/650
1950     1001N – 1616ON
1951     101NA – 15808NA
1952     15809NA – 25000NA
(then) 25000 – 32303
(no suffix)
1953     32304 – 44821
(no suffix)
1954 101 – 8517   44822 – 56699
(no suffix)
1955 8518 – 17388   56700 – 70929
(no suffix)
1956 17389 – 26275   70930 – 82797 (then)
0101 – 0944
1957 26276 – 35846 H101 – H760 0945 – 011165
(first year for 500 unit construction)
1958 35847 – 45311 H761 – H5484 011166 – 020075
1959 45312 – 59359 H5485 – HI 1511 020076 – 029633
1960 59360 – 69516 H11512 – H18611 029634 – 030424
(first year for 500 unit construction)
1960     (then) D101 – D7726
1961 69517 – 81889 H18612 – H25251 D7727 – D15788
1962 81890 – 88346 H25252 – H27932 D15789 – D20308

Triumph Alpha-Numeric prefix numbering system started in 1969

A Triumph T140V with a motor number of T140V NP79000 would have been manufactured in October 1976 (N) for the 1977 Model year (P).

MONTH OF MANUFACTURE YEAR OF MANUFACTURE
A January C 1969
B February D 1970
C March E 1971
D April G 1972
E May H 1973
G June J 1974
H July K 1975
J August N 1976
K September P 1977
N October X 1978
P November A 1979
X December B 1980