Genuine Husqvarna Flat Idler Pulley 
Part #: 539919078

Fits these models and more:
Husqvarna
W 3212 (2001-02) Lawn Mower
W 3212 A (539104773-01) (2000-02) Lawn Mower
W 3213 (2001-02) Lawn Mower
W 3213 (968999114) (2004-11) Lawn Mower
W 3213 A (539104773-01) (2000-02) Lawn Mower
W 3612 (2001-02) Lawn Mower
W 3612 A (539104773-01) (2000-02) Lawn Mower
W 3613 (2001-02) Lawn Mower
W 3613 (968999116) (2004-11) Lawn Mower
W 3613 A (539104773-01) (2000-02) Lawn Mower
W 3613 ETS (968999117) (2001-09) Lawn Mower
W 3614 (2001-02) Lawn Mower
W 3614 A (539104773-01) (2000-02) Lawn Mower
W 4814 (2001-02) Lawn Mower
W 4814 A (539104773-01) (2000-02) Lawn Mower
W 4815 (2001-02) Lawn Mower
W 4815 (968999251) (2004-11) Lawn Mower
W 4815 A (539104773-01) (2000-02) Lawn Mower
W 4815 ETS (968999120) (2001-09) Lawn Mower
WG 3213 P (968999114) (2005-08) Lawn Mower
WG 3613 BF (968999365) (2006-02) Lawn Mower
WG 3613 E (968999117) (2006-02) Lawn Mower
WG 3613 EC (968999756) (2006-02) Lawn Mower
WG 3613 P (968999116) (2005-08) Lawn Mower
WG 4815 (968999278) (2004-11) Lawn Mower
WG 4815 E (968999120) (2006-02) Lawn Mower
WG 4815 P (968999278) (2005-08) Lawn Mower
WH 3614 (2001-02) Lawn Mower
WH 4817 A (2000-06) Lawn Mower
Wh 4817 E (968999238) (2005-08) Lawn Mower
WH 4817 EFQ (968999252) (2005-08) Lawn Mower
WH 4817 EFQ (968999252) (2008-08) Lawn Mower
WH 4817 ETS (968999123) (2006-02) Lawn Mower
WH 5219 EFQ (968999253) (2005-08) Lawn Mower
WH 5219 EFQ (968999253) (2008-08) Lawn Mower
WH 5221 EFQ (968999599) (2008-08) Lawn Mower
WHF 4215 ETS (968999127) (2001-12) Lawn Mower
WHF 4215 ETS (968999127) (2002-02) Lawn Mower
WHF 4215 ETS (968999127) (2002-09) Lawn Mower
WHF 4817 (968999252) (2004-09) Lawn Mower
WHF 4818 ETS (968999129) (2001-12) Lawn Mower
WHF 4818 ETS (968999129) (2002-02) Lawn Mower
WHF 4818 ETS (968999129) (2002-09) Lawn Mower
WHF 5218 ETS (968999130) (2001-12) Lawn Mower
WHF 5218 ETS (968999130) (2002-02) Lawn Mower
WHF 5218 ETS (968999130) (2002-09) Lawn Mower
WHF 5219 (968999253) (2004-09) Lawn Mower
WHT 3615 (968999237) (2004-09) Lawn Mower
WHT 4817 (968999238) (2004-09) Lawn Mower
WH 5219 EFQ (968999253) (2006-12) Lawn Mower
WH 5221 EFQ (968999599) (2006-12) Lawn Mower
DT 20 Dethatcher
DTB 20 Dethatcher
DTH 20 Dethatcher
DT 20 A (539104746-02) (2000-05) Dethatcher
H348F (2009-12)(966529102) Collection System
RZ4216 (966455801) Riding Lawn Mower
EZ52 (966004701) (2010-10) Grass Collector
H352F (966529103, 966805003) (2009-12) Grass Catcher
H242 (966529201) (2009-12) Collection System Zero Turn
966805002 (2011-07) Collection System, 42 Inch, 48 Inch
966793001 (2012-05) Collection System
966792901 (2012-05) Collection System
966792801 (2012-05) Collection System
966792701 (2012-05) Collection System
966656603 (P-ZT61) Collection System
966656602 (P-ZT52) Collection System
966656601 (P-ZT48) Collection System
966529401 (966792701, RZ42F) (2009-11) Collection System
966004801 (2009-05) Collection System, 61 Inch
COLLECTION SYSTEM, 52 INCH (2009-05) Collection System Zero Turn
587960201 (2015-01) Collection System, 48 Inch
WGP3616 (966638501) (2010-10) Lawn Mower: Commercial Walk Behind
WGP4818 (966638502) (2010-10) Lawn Mower: Commercial Walk Behind
WH3615 (968999237) (2005-08) E Lawn Mower: Commercial Walk Behind
WH3615 (968999111) (2001-02) A Lawn Mower: Commercial Walk Behind
WH4817 (968999123) (2006-02) Ets Lawn Mower: Commercial Walk Behind
WH4817 (968999238) (2005-08) E Lawn Mower: Commercial Walk Behind
WH4817 (968999106) (2001-02) A Lawn Mower: Commercial Walk Behind
W3213P (968999364) (2008-06) Lawn Mower: Commercial Walk Behind
W3613P (968999116) (2008-06) Lawn Mower: Commercial Walk Behind
RC 318T (967628701) Rider
965996885 (2010-07) Rider 111 B
965996801 (965996885, 966663185, 967186501) (2011-02) Rider 111 B
RC 320TS AWD (967628801) Rider
B5 (965996785) (2010-07) Rider 111
B5 (965996701, 965996785, 966663085, 967186401) (2011-02) Rider 111
R112 C (967178401) (2014) Rider
R112 C5 (967178501) (2014) Rider
R115 B (967149601, 967181601) (2013-01) Rider
R115 C (967252701) (2014) Rider
R120 S (9671818-01) (2013-01) Rider
BZ 27 (968999315) (2006-04) Zero Turn: Commercial
BZ 27 (968999315) (2007-03) Zero Turn: Commercial
BZ 27 D (968999315) (2009-07) Zero Turn: Commercial
BZ 27 D (968999315) (2006-05) Zero Turn: Commercial
BZ 34 (968999316) (2006-04) Zero Turn: Commercial
BZ 34 (968999316) (2007-03) Zero Turn: Commercial
BZ 34 D (968999316) (2006-05) Zero Turn: Commercial
BZ 6127 D (968999218) (2004-11) Zero Turn: Commercial
BZ 6127 D (968999218) (2003-06) Zero Turn: Commercial
BZ 6127 TD (968999262) (2005-11) Zero Turn: Commercial
BZ 6134 D (968999214) (2004-11) Zero Turn: Commercial
BZ 6134 D (968999214) (2003-06) Zero Turn: Commercial
BZ 6172 D (968999369) (2005-11) Zero Turn: Commercial
BZ 7234 D (968999370) (2005-11) Zero Turn: Commercial
BZ 7234 D (968999216) (2004-11) Zero Turn: Commercial
BZ 7234 D (968999216) (2003-06) Zero Turn: Commercial
BZ 7234 TD (968999264) (2005-11) Zero Turn: Commercial
BZE 6127 D (968999221) (2005-02) Commercial Zero Turn For Serial No. 033600000 & Higher
BZE 6127 D (968999221) (2004-01) Commercial Zero Turn For Serial No. 033600000 & Higher
BZE 6134 D (968999222) (2003-06) Zero Turn: Commercial
BZE 6134 D (968999222) (2005-02) Commercial Zero Turn For Serial No. 033600000 & Higher
BZE 6134 D (968999222) (2004-01) Commercial Zero Turn For Serial No. 033600000 & Higher
BZE 7234 D (968999223) (2003-06) Zero Turn: Commercial
BZE 7234 D (968999223) (2005-02) Commercial Zero Turn For Serial No. 033600000 & Higher
BZE 7234 D (968999223) (2004-01) Commercial Zero Turn For Serial No. 033600000 & Higher
968999153 (2000-06) Zth 5223A Zero Rider
ZTH5225A (968999154) (2000-06) Zero Turn: Commercial
966792701 (2012-05) Collection System
RZ 19 CE (966658901-02) (2011-13) Zero Turn: Consumer
RZ 4216 CA (966612402) (2011-02) Zero Turn: Consumer
RZ 4216 CA (966503901) (2010-01) Zero Turn: Consumer
RZ 4219 (966809001, 250200) (2011-09) Zero Turn: Consumer
RZ 4219 BF (967176102) (2013-11) Zero Turn: Consumer
RZ 4219 BF (966676601) (2011-02) Zero Turn: Consumer
593024301 (2018-02) Street Brush
T-60368 (596289801)(2018-12) Flail Mower
C103 (967978101)(2019-01) Cutting Deck
C103 (967628901) Cutting Deck
C112 (967693701)(2019-01)(967978201)(2019-06)(2019-06) Cutting Deck
C112 (967 62 90-01) Cutting Deck
DTH 20A (968999192)(2000-09) Dethatcher
BX 34 D (968999316)(2009-07) Zero-Turn Mower
BZ 6127 (2005-01) 61 Inch Zero-Turn Mower
BZ 6127 D BF (968999369)(2005-08) 61 Inch Zero-Turn Mower
BZ 7234 (2005-01) 72 Inch Zero-Turn Mower
BZ 7234 D BF (968999370)(2005-08) 72 Inch Zero-Turn Mower
RZ 4221 BF (967176101)(2012-06) 42 Inch Zero-Turn Mower
ZTH 5223 A (968999153)(2000-06) 52 Inch Zero-Turn Mower
ZTH 6125 A (968999155)(2000-06) 61 Inch Zero-Turn Mower
WH 3615 A (968999111)(2000-06) 36 Inch Walk-Behind Mower
WH 3615 A (968999111)(2001-02) 36 Inch Walk-Behind Mower
WH 3615 E (968999237)(2005-08) 36 Inch Walk-Behind Mower
966004401 (2009-05) 44 Inch Grass Collection Blower Kit
966529101 (2009-12) 42 Inch Grass Collection System
966529102 (2009-12) 48 Inch Grass Collection System
966529103 (2009-12) 52 Inch Grass Collection System
Poulan
380ZX Lawn Tractor
Jonsered
FR2311 M 966639785 - 966639701 (2011-02) Frontrider
FR2312 MA 966639885 - 966639801 (2011-02) Frontrider