I did not do any Research but i have built and helped build some "T's" a "TT" also.
I worked with some real experts.
One worked in the Ford assembly plant in Denver ( building is still there on s Broadway.)
And wish they where still alive. as to modeling a "TT" don't worry about spring leaf count it is very hard to tell any of them apart.
unless you have them laying right next to each other the spring center bolt for a "TT" is longer but not all that much.
Kelsey-Hayes made some after market parts for "TT" truck's as did many other company's and your local Ford dealer
would order them for you or sears, monkey ward's, western auto etc on and on
worm drive rear end some with 2 speed" Ruckstell 2 speed rear axle. .
about 20 mph is all your going to get out of a "TT"
the back end of "TT" front fenders have no running board holes.
and no running board holes on back fender they were called Commercial fenders and they mount and look different.
Mountain brakes mount out side the drum and the emergency brake in side and the inside brakes were lined like the other's
cloth webbing belt's brass riveted to the shoe's and some now replace the webbing with Kevlar lining .
that can be hard on the old drums but it is ok i guess . 26/27 tranny drums were bigger and some refitted them to older tranny's .
sliding thru an intersection back wheels locked up is no fun one must plan ahead for stopping.LOL.
mountain brakes help with keeping the other brake cooler on a down grade but if you brake band is ok you could lock up the rear
axle no sweat just stomping on the brake pedal unless you hit a double neutral then the mountain brake might save you.
your ford dealer would paint your car or truck any color you wanted and ad any thing made for your car or truck at a extra cost of course.
so modeling a "T" or a "TT" you have some leeway it's not set in stone. have fun folks