T-belt maintenance shopping list for a 928GTS, please visit for more info and accurate prices: 

Part number Part Description Replace along with T-Belt Price (approx) Pic
928 105 157 50 Timing Belt (83-95) yes 43 $
928 105 552 08 Tensioner Rubber End Boot (85-95) if in bad condition 21$
999 512 564 02 Tensioner End Boot Clamp (83-95) if in bad condition 3.5 $
999 701 650 40 Tensioner Piston O-ring yes 1.5 $
900 123 144 30 Tensioner Filler Plug Seal (10 mm)
900 123 102 30 Tensioner Bleed Screw Seal (6 mm)
928 105 611 05 Tensioner Mounting Gasket if in bad condition 12 $
928 105 613 04 Tensioner Arm Carrier Bushings (2) if in bad condition 22 $
928 105 512 12 Tensioner Roller (78-95) if in bad condition 75 $
928 105 571 04 Idler Roller (78-95) if in bad condition 76 $
928 106 015 20 Water Pump (87-95) some say "always" 195 $
928 106 134 05 Water Pump Gasket some say "always" 2$
928 105 067 00 Lower Guide Roller if in bad condition 190$
N 012 408 2 Clip for lower Roller if in bad condition 1$
999 113 275 40 Oil Pump Shaft Seal 20$
999 701 633 40 Oil Pump Body O-ring Seal 5$
999 701 006 40 Oil Pump Bolt O-rings (3)
999 113 263 40 Main Crankshaft Seal 25$
999 113 282 40 Camshaft Seals (2)
999 701 602 40 Camshaft O-ring (Large) (2)
999 701 595 40 Camshaft O-ring (Small) (2)
928 105 184 00 Camshaft Housing End Seal (2)
928 107 169 01 Oil Drain Pipe Gasket
928 606 213 03 Oil Level Sender Gasket 1$
900 174 044 40 Oil Dip Stick Tube Seal Ring 1$