TM or not
The easiest way is of course to measure. The I on the std. rig is 38, the TM is 41, and the P (mainsail luff) is 31.5 and 34.5 respectively. The actual numbers on the TM seem to vary slightly without consistency, but if you do the following measurements you will know at least which model you have:
For the I, snap a tape measure on the genoa halyard and raise up just until the halyard stops, but not jamming the shackle into the halyard sheave-then take your mesaurement to the deck right at the spot where the Upper shrouds go through the deck. Is this is more than 38, you have the Tall rig. Or, provided you have a fixed gooseneck (some do, some do not), measure down from the hoisted main halyard (as you did with the genoa halyard) to the top of the boom or the top of the black band near the boom (if one is fitted). If you have a gooseneck track instead of a fixed one, note the usual spot where the boom sits and use this point-either way, if the number is larger than 31.5-32'-you have the TM.
The sails may also be indicators (but not as reliable-since there are quite a few sails out there which do not really fit the boat). But if you lay them out and measure the luff of the main and get a length much larger than 32.5 (the real number should be 31.5 for std rig)-this 32.5 number allows for the possibility you were setting the boom in the lowest spot on the track-for sure you have the TM. Likewise if the luff of the largest genoa is longer than 38.5 (to allow for extreme aft rake in the mast), you have a tall rig.
Of course you may have luff lengths SHORTER than 31.5 for the main and 38 for the genoa, and you could still have either rig-this would be because the sails being measured did not fit properly-so the only thing you can infer from sail dimensions is that if they are longer than would be found on the std rig and fit the boat OK, then you have the TM..
There is more to measuring a boat-but this was to try and answer your question. There are a series of measurements needed by a sailmaker to build a sail that really fits well-if you want more info on that let me know.
Cheers,
S