right through the frame but I didn't think much of the upper mount pieces included with the kit so I made my own, they are a whole lot stronger plus needed them wider because what they sent wasn't long enough to clear the I beam frame. I would've mounted them on the outside or tire side but the gas line on the one side didn't leave enough clearance for my comfort levels so I opted for the inside. when I can I will take better pics. I probably will add second shear mounts for the shocks at a later date, on both the axle and frame. what is there should be good enough for now imo. I didn't weld the new mounts on and probably would feel better if I did but what I built should do the job since they are just shock absorbers and not air's or coil overs. I did buy them longer than specified and mounted them with the hangers pointed down because I plan on changing the tire out from the 225 15's to 235 16's and will need an extra inch of height so probably a 2" lift at some point and this should accommodate that. I messed up when I ordered the kit a while back and didn't know that each kit was for tandem so I ordered qty 2 so I have another kit for another tandem axle trailer lol i'll have to put it up for sale once i'm done.
another option Dexter Axle - Trailer Axles and Running Gear Components - K71-175-01 Shock Kit