8 - 06034479 1x BOLT, Hex Head, .375-16x2.25
11 - 06034452 1x STUD, .375-16x.375-16x2.38
13 - 06034453 2x STUD, .375-16x.375-16x1.63
Most of those screws are standard - in order, here are the fractional callouts for those screws:
#8 is 3/8"-16x2-1/4"
#11 is 3/8"-16x2-3/8" OAL stud
#13 is 3/8"-16x1-5/8" OAL stud.
Often, studs can be cut-to-order from suitable threaded rod, but I prefer to use CRES, brass, or bronze - using zinc-plated carbon steel requires that you then dress the cut ends, since that's exposed steel and the stud would "hollow out" if it starts rusting (since I prefer to replace water-involved fasteners with brass or bronze anyhow, that works out. CRES threaded rod is harder to find.)
Using those fractional callouts, you should be able to pick up replacement screws at the hardware store or Fastenal - if you have a hardware store you can trust to not stock Chinese crap. However, note that hardware stores usually have screws over 1" long in increments of 1/4", so you may need to buy flat washers to keep the screws from bottoming out in blind holes. The typical flat washer runs 0.030"-0.040" thick; 1/16"=0.0625", 1/8"=0.125". The typical flat washer is about 1/32" thick - 1/32" = 0.03125"
(Yeah, it gets helpful to know these conversions offhand - but you can also usually find a small rule in the Tools section of the hardware store that has these listed on the back - along with common tap drill sizes and the like. If you see one, buy it!)