Hello Again Bob: Go to the Parker Collectors website & click on
www.parkerguns.org/ Scroll down the left side & click on Parker identification. Yours will be at the very end under "Dollar Grades, T Latches & Back Actions" your will be very near the bottom. Lifter Parkers were the second mechanism employed by Parker soon after the Civil War. It derives it's name for the lifter mechanism under the action by which you unbreach the gun. The first mechanism is referred to as the "T Latch" The third and on all employed the top lever for unbreaching.
You can then scroll back up & click "Ordering a Parker Research Letter" that will give you all the info. You should also think bout joining the PGCA. Research letter are less expensive for members than for non-members.
IMHO stands for "In My Humble Opinion"
Best Regards, George