Table:
text: Yellow Coach Manufacturing Company
P-series (1939-1944)
P-series (1939-1944)
Model Built Quantity Seats Length_ Engine
PG-2501 1939–1940 8 25 ft1in (m) GMC 248 6 cyl. gas
PG-2502 1939–1940 66 25 ft1in (m) GMC 308 6 cyl. gas
PG-2503 1941 4 25 ft1in (m) GMC 248 6 cyl. gas
PG-2504 1940–1941 70 25 ft1in (m) GMC 308 6 cyl. gas
PG-2505 1941–1942 118 25 ft1in (m) GMC 308 6 cyl. gas
PG-2901 1939–1940 50 29 ft0in (m) GMC 426 6 cyl. gas
PD-2901 1939–1940 16 29 ft0in (m) GMC 4-71 4 cyl. diesel
PG-2902 1940–1941 56 29 ft0in (m) GMC 426 6 cyl. gas
PD-2902 1941–1942 249 29 ft0in (m) GMC 4-71 4 cyl. diesel

Question: What is the quantity of PG-2901 engine model for Yellow Coach Manufacturing Company?