your old bumper is period correct. the lack of holes tells the story. if you look, your new bumper has many more holes because it is setup to accommodate every option available. early models only had holes for early options.
I have never noticed any difference in a later style starting in 62 to the start of 75. Besides the holes on the bottom of my FJ25 being in a different location and only using two carriage style bolts on each instead of three those were the same also. Two locations for the license plate bracket. One in between the frame horns and one to the right side when a PTO winch was installed. Two holes for the PTO winch. Then holes outside the frame rail for the fog lights. License plate bracket, fog lights, PTO winch, what other option were available? My 10/76 has more holes but I can't swear it is original to the cruisers. A friend of mine gave me his bumper off of a 1/75 FJ40. He put a channel iron bumper and Warn winch shortly after buying the cruiser new. I still have the bumper. Easy for me to tell which one it is. My 68 which I bought in 74 had extra brackets on the ends that ran back and bolted to the back holes for the PTO winch. They look so professional made I thought at the time they were OEM. I drilled the 75 bumper to use them.
Also noticed on pics I got from fjfjfj the inside of the rear sill is different: mine has no reinforcements in it.
If by reinforcements your talking about the U shaped channel that runs against the bac and roll with the outside corner than your has been changed. That U shaped channel goes back to the FJ25 and maybe earlier. Never seen a BJ in person to look.
I understand that 1962 was a transition year for the Landcruiser. They used FJ25 parts and FJ40 parts on the same vehicles.
61 was the closest to the FJ25. Inlet on the apron for the oil bath air cleaner. Large gas cap. Early front bumper. A bracket welded to the front of the wheel wells for the arms on the front of the jump seats. Jump seat arms were lower than the FJ25 but still had arm rests on the front.
Two 61 FJ40s VINs 1FJ40~10202 ahd 1FJ40~10939.
Two 62 FJ40s one is the soft top tub I picked up. Was sold as a 63 but because there was a old insurance card inside I know the VIN. Won't post that one since the frame, VIN plate and title were sold to TLC to made into a Icon. I didn't sell it just bought the tub. That one is a little lower than 15000. Second one is 2FJ40~15956.
JohnnyC and I figured Toyota started the FJ40 VIN numbers at 1FJ40!~10001. The production numbers don't add up to eleven thousand units in 61 Then only in the 16,000 range in 62. What I find strange is a lack of VINs in the 11/12/13 thousand range. Curious were sales so bad in the US that after importing a couple hundred 61s Toyota waited until sometime in 62 to import more?