All Time UP Diesel Roster, S Series Yard Slugs

Yard Slug — 6 units
B-B trucks; (no engine); 235,300 pounds operating weight

Road Number	Rebuild Date	Rebuilt From	Date Retired	Notes
UP S1	Dec 1973	UP GP9B 176B	9 Feb 1987	Out of service June 1986; sold to Aaron Ferer & Son, Omaha, Neb., in November 1987.
UP S2	Jun 1974	UP GP9B 341B	9 Feb 1987	Out of service May 1985; sold for scrap to Southwest Railroad Car Parts, Longview, Tex., 2 April 1987.
UP S3	Oct 1974	UP GP9B 301B	10 Sep 1982	Scrapped by UP at Omaha in September 1982.
UP S4	26 Sep 1975	UP GP9B 316B	28 Aug 1989	Sold for scrap to Pielet Brothers Scrap Iron & Metal, McCook, Ill., 17 January 1990.
UP S5	9 Mar 1976	UP GP9B 314B	24 Apr 1989	Out of service April 1986; sold for scrap to Pielet Brothers Scrap Iron & Metal, McCook, Ill., 17 January 1990.
UP S6	22 Sep 1976	UP GP9B 306B	28 Aug 1989	Sold for scrap to Pielet Brothers Scrap Iron & Metal, McCook, Ill., 17 January 1990.

General Notes:

a.	UP S1 to S6 were built by UP at Omaha from retired UP GP9Bs.
b.	UP S1, S2, and S3 were originally equipped to operate only with SD7 slug control units. S4, S5, and S6 were originally equipped to operate only with SD24 slug control units; all were later modified to operate with either SD7, SD24, and later, SD40 slug control units; these combinations were called ten motor slug sets.
c.	Prior to being rebuilt to Slug S5, GP9B 314B was out of service for 239 days, since July 1974, because of an electrical fire.
d.	UP S4 and S5 were equipped with external sand boxes in October 1980, similar to those applied to the DDA40X, DDA35, and DD35 B-unit road freight locomotives.
e.	Car body of UP S6 was cut down to 77 inches in May 1985 at Salt Lake City, to improve visibility from the attached power unit.

Yard Slug — 2 units
C-C trucks; 393,000 pounds operating weight

Road Number	Rebuild Date	Rebuilt From	Date Retired	Notes
UP S7	31 Jan 1978	UP SD24B 406B	17 Jul 1989	Sold for scrap to Pielet Brothers Scrap Iron & Metal, McCook, Ill., 17 January 1990.
UP S8	Dec 1978	UP SD24B 444B	9 Feb 1987	Wrecked during late April 1985 at North Platte, Neb.; out of service May 1985; sold for scrap to Aaron Ferer & Son, Omaha, Neb., in November 1987.

General Notes:

a.	UP S7 and S8 built by UP at Omaha from retired UP SD24Bs.
b.	UP S7 and S8 were originally equipped to operate only with SD24 slug control units; both units were later modified to operate either with SD24 or SD40 slug control units; these combinations were called twelve motor slug sets.

Yard Slug Model SL-1 — 23 units
B-B trucks; 256,000 pounds operating weight

Road Number	Previous Number	Date To UP Number	UPY Number	Date To UPY Number	Date Retired	Notes
UP S9	MP 1400	19 Aug 1986	UPY 903	10 May 2003		1
UP S10	MP 1401	30 Sep 1986	UPY 904	1 Sep 2000
UP S11	MP 1402	13 Jul 1990	UPY 905	6 Mar 2002
UP S12	MP 1403	29 Jan 1988
UP S13	MP 1404	29 Jan 1987	UPY 102	22 Jan 2002	25 May 2001	2
UP S14	MP 1405	16 Mar 1988			31 Aug 2000
UP S15	MP 1406	27 Jan 1988			31 Aug 2000
UP S16	MP 1407	21 Aug 1988	UPY 910	12 Feb 2003
UP S17	MP 1408	21 Aug 1988	UPY 911	22 Apr 2002
UP S18	MP 1409	3 Oct 1988
UP S19	MP 1410	11 Nov 1986	UPY 913	13 Feb 2004
UP S20	MP 1411	25 Sep 1986	UPY 100	10 Dec 2001	29 Nov 2000	2
UP S21	MP 1412	10 Jan 1986	UPY 915	6 Nov 2003
UP S22	MP 1413	10 Mar 1986	UPY 916	11 Mar 2002
UP S23	MP 1414	11 Mar 1986
UP S24	MP 1415	26 Dec 1985				3
UP S25	MP 1416	31 Mar 1986				3
UP S26	MP 1417	19 Oct 1987	UPY 101	22 Jan 2002	19 Dec 2000	2
UP S27	MP 1418	28 Jan 1988	UPY 921	23 Mar 2001
UP S28	MP 1419	3 Oct 1988
UP S29	MP 1420	30 Sep 1988	UPY 923	11 Oct 2001
UP S30	MP 1421	9 Sep 1988	UPY 924	20 May 2000
UP S31	MP 1422	1 Feb 1988	UPY 925	18 Feb 2000

General Notes:

a.	Rebuilt from retired MP SW7s, SW8s, and SW9s by MP Pike Avenue Shops, North Little Rock, Ark.; mated with MP15s and, beginning in October 1990, GP38-2s.
b.	UP S16-S18 (as MP 1407-1409) were first painted UP yellow and gray, with Missouri Pacific lettering, in May and July 1985 while assigned to Houston; relettered to UP S16-S18 in August and October 1988.
c.	Renumbered to UPY 903-925.
d.	Individual unit histories:

Note:

1.	UP S9, as MP yard slug 1206, was completed as MP's first yard slug in November 1978 and was initially mated with MP SW1200 1275; MP 1206 was renumbered to MP 1400 on 30 December 1978.
2.	UP S13, S20, and S26 were converted in December 2001 and January 2002 for service as CCRCL control units for remote control switcher/slug power sets; completed as UPY 100-102.
3.	UP S24 and S25 were retired in December 2000; reinstated on 11 January 2001, but as of February 2008, the units remain stored at Pine Bluff, Ark. (information from Kermit Geary, via email to LocoNotes discussion group, February 13, 2008)

Yard Slug Model SL-4B — 3 units
B-B trucks; 262,000 pounds operating weight

General Notes:

a.	Original total of four units; three units went to UP at merger; SP retired 1011 prior to the merger.
b.	SP 1010-1013 were rebuilt by General Electric, Minneapolis, from four former L&N switchers (three NW2s and an SW7); all were initially assigned to Roseville, Calif., with MP15ACs.
c.	Assigned UP S1-S3 in September 1997, not renumbered; assigned UPY 900-902 in December 1999, not renumbered.