if you go to the gallery, then do a search for "T-20" then one for "baker hill" you will get tons of pics of each. look them over and you will be able to tell what it has when you go look at it. take some 220 grit sand paper with you when you go look at the machine. if it's a first gen the outer frame rails will be flat steel. a 2nd gen will have "C channel" outer rails and a cross section will look like this [ . if it is a 2nd (and the guy will let you) sand the top of the right rear frame rail above the axle. some numbers should appear (take a putty knife to scrape 30+ year of grease before you start sanding). of the numbers that you find, 2 will be larger than the rest. those are the year ie" 76 or 81. if it was made before 76 it is abs and cracks can be repaired with a goop made from abs scraps melted in acetone. 76 and later it's HDPE and can only be plastic welded.
also if the guy will let, you sand the side of the upper body toward the front.( in the area where it has 295 wild wolf in this pic) if the model name stickers were there for any length of time, sun will have faded the plastic around them a little. after you've sanded the area to bare yellow plastic, pour a little water on the area and you should be able to see the model name/ number. report that back here and we can probably tell you a lot more about the machine.
good luck
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