Ferris OEM Knee Pad For SRS Z1 Stand On Zero Turn Mowers. Old Part Number:5104936. New Part Number: 5108193FS. Fits the following models. 5901546 – SRS Z1 Series w/ 36 Mower Deck (SRSZ1KAV1936). Operator Compartment Group S/N 2017954955 & Below. Operator Compartment Group S/N 2017954956 & Above. 5901547 – SRS Z1 Series w/ 48 Mower Deck (SRSZ1KAV2248). 5901550 – SRS Z1 Series w/ 36 Mower Deck (SRSZ1BV2336). 5901675 – SRS Z1 Series w/ 48 Mower Deck (SRSZ1BV2348). 5901676 – SRS Z1 Series w/ 36 Rear Discharge Mower Deck (SRSZ1KAV1936RDCE). 5901677 – SRS Z1 Series w/ 48 Rear Discharge Mower Deck (SRSZ1KAV2248RDCE). 5901678 – SRS Z1 Series w/ 36 Mower Deck (SRSZ1KAV1936 CAL). 5901687 – SRS Z1 Series w/ 48 Mower Deck (SRSZ1KAV2248 CAL). 5901939 – SRS Z1 Series w/ 36 Mower Deck (SRSZ1, 36, K19, NA). 5901940 – SRS Z1 Series w/ 48 Mower Deck (SRSZ1, 48, K22, NA).