Joe Montana has the most passing yards by a 49ers quarterback in a game, with 476 yards versus the Falcons on October 14, 1990.

which 49ers qb has the most rushing passing yards in a game
Interpreted as:
Which 49ers qb has the most rushing passing yards in a regular-season game?
10/14/1990Montana11/28/1993Young12/11/1989Montana9/13/1992Young11/17/1986Montana12/5/1999Garcia10/6/1985Montana9/24/1989Montana12/18/1995Young11/17/2019Garoppolo10/10/2004Rattay12/2/2018Mullens9/8/2013Kaepernick11/4/1990Montana11/21/1982Montana12/17/2000Garcia10/18/1992Young11/6/2016Kaepernick9/23/1990Montana12/8/1996Young9/16/1990Montana9/27/1998Young11/20/1995Grbac476462458449441437429428425424417414412411408402399398398393390387382
NAMEDATETMOPPPASS YDSRUSH YDSCMPATTPCTAVGTDTD%INTINT%SCKSCKYRATE
Joe MontanaJoe Montana10/14/1990SFSF@ATLATL4764324965.39.7612.224.1434119.6
Steve YoungSteve Young11/28/1993SFSF@RAMRAM4623263281.314.4412.513.1310145.3
Joe MontanaJoe Montana12/11/1989SFSF@RAMRAM45812304271.410.937.124.8219111.0
Steve YoungSteve Young9/13/1992SFSFvsBUFBUF44950263770.312.138.112.7110127.0
Joe MontanaJoe Montana11/17/1986SFSF@WASWAS4419336055.07.400.035.032357.7
Jeff GarciaJeff Garcia12/5/1999SFSF@CINCIN43712334967.38.936.112.000107.3
Joe MontanaJoe Montana10/6/1985SFSF@ATLATL4296375764.97.558.800.019116.8
Joe MontanaJoe Montana9/24/1989SFSF@PHIPHI42814253473.512.6514.712.9843142.8
Steve YoungSteve Young12/18/1995SFSFvsMINMIN4258304961.28.736.124.11092.6
Jimmy GaroppoloJimmy Garoppolo11/17/2019SFSFvsARIARI4247344575.69.448.924.4216115.4
Tim RattayTim Rattay10/10/2004SFSFvsARIARI41714385766.77.323.500.052699.8
Nick MullensNick Mullens12/2/2018SFSF@SEASEA4141304862.58.624.212.132895.3
Colin KaepernickColin Kaepernick9/8/2013SFSFvsGBGB41222273969.210.637.700.028129.4
Joe MontanaJoe Montana11/4/1990SFSF@GBGB41113254062.510.337.500.000122.0
Joe MontanaJoe Montana11/21/1982SFSF@STLSTL4086263966.710.537.712.6437116.2
Jeff GarciaJeff Garcia12/17/2000SFSFvsCHICHI40215364481.89.124.500.0423119.9
Steve YoungSteve Young10/18/1992SFSFvsATLATL39928182864.314.3310.713.600128.6
Colin KaepernickColin Kaepernick11/6/2016SFSFvsNONO39823243961.510.225.112.615102.3
Joe MontanaJoe Montana9/23/1990SFSFvsATLATL39812243568.611.425.700.0319125.7
Steve YoungSteve Young12/8/1996SFSFvsCARCAR39363274165.99.637.324.9518101.0
Joe MontanaJoe Montana9/16/1990SFSFvsWASWAS3903294465.98.924.512.30099.6
Steve YoungSteve Young9/27/1998SFSFvsATLATL38750283971.89.937.712.6310118.2
Elvis GrbacElvis Grbac11/20/1995SFSF@MIAMIA3823314175.69.349.800.016136.4
Jimmy GaroppoloJimmy Garoppolo12/17/2017SFSFvsTENTEN3810314372.18.912.300.0318106.8
Joe MontanaJoe Montana9/10/1984SFSFvsWASWAS38114244060.09.525.000.0214108.4
Results may be incomplete. StatMuse has complete game-level data for rushing yards going back to the 1960 season.

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