Subfloor plywood thickness 20 years ago vs today

[mjzraz]

I am replacing a few sheets of subfloor plywood in the center of a room due to water damage. The Existing subfloor is Georgia Pacific 19/32" Sturd-I Floor plywood that is 20-25 years old. 19/32" is stamped on the underside.
I went to the lumber yard and they didn't carry 19/32 GP Sturd I Floor, but they did have 19/32" LP TopNotch 250 T&G Subflooring. (they referred to it as " 5/8" Subfloor ")
I am hesitant to buy anything and I don't have an easy way to measure the thickness of the existing floor and don't trust measuring any of the plywood in the area of the water damage due to swelling, etc. Before I understood there were different strengths of plywood, I got some 19/32" SHEATHING Grade plywood for floor damage in the bathroom near the tub. There was a slight difference in height of the floor, but I was putting concrete backer board over the entire floor so I just put more thinset under that section to level it before I started laying the backer board.
After all that, My question is was 19/32" subfloor plywood thicker 20-25 years ago, or should I be able to get the LP Topnotch 19/32"? and have it match in height.

[pushkins]

Trying to get an accurate measurement of 20 year old wood is almost impossible, expansion/contraction/being down and dry for 20 years/or being down and wet makes it almost impossible.
You are correct to put down 5/8" as a sub floor and even more correct to use thinset to make up any difference in heights.

No 19/32 20 years ago is typically the same as 19/32 today, but for the previously mentioned reasons there will be subtle differences between old and new this is really not all that uncommon.

[HayZee518]

dimension lumber has gotten thinner and more expensive. in the 1960's 3/4 plywood was 3/4 plywood. rough cut 2X4s were actual 2X4. millgrade lumber is 1 1/2 X 3 1/2 - for a 2X4. underlayment or sheathing is now 5/8s instead of 3/4.