Great story that otherwise would have probably been lost. Thank you sir! The standard gear ratio gives the 70 ton a maximum speed of 55 mph but in reality the truck design limits it to 45 mph for the same reason EMDs without flexicoils.

Were the PTC units equipped with 65:12 gearing - otherwise they would have been even higher geared with 62:15.

Another question regarding SP units - consider the purchase and retirement dates as most equipment trusts are 15 years. At least some of the 70 tons were bought new by SP Equipment if this makes any difference.

5100 1949-1977 resold
5101 1949-1968 resold
5102 1949-1965 to ALCO
5103 1949-1975 resold
5104 1949-1961 resold
5105 1949-1961 resold
5106 1949-1968 retired San Diego; salvaged/scrapped at Eugene
5107 1949-1966 scrapped at Sacramento as credit against EMD SD45
5108 1949-1967 resold SMV and salvaged for parts
5109 1949-1974 resold

All the original order were in service for at least 15 years on the SP except 5104 and 5105 which were sold to Weyerhaeuser Timber Company for use. (Did WTCO lease SP 70 tons previous?) Not that the majority were resold for further use.

5110 1950-1964 sold for scrap
5111 1950-1962 scrapped at Sacramento
5112 1950-1963 sold for scrap
5113 1950-1964 to EMD

Note that none of the four 1950 units made their full 15 years of service and all were scrapped.

5114 1951-1972 resold (1950 built 2nd GE demonstrator)
5115 1951-1967 to EMD against SD45
5116 1951-1964 to EMD
5117 1951-1966 resold
5118 1951-1964 to EMD
5119 1955-1967 resold
5120 1955-1972 sold (reuse or scrap?)

It seems odd that SP would retire units less than 15 years old (and potentially still under their equipment trusts) instead of older units. It makes me wonder if any of the early scrap units were wrecked or had blown engines.

Retirements by year (units on roster after retirements):

1960: (21)
1961: (19) 5104 5105
1962: (18) 5111
1963: (17) 5112
1964: (13) 5110 5113 5116 5118
1965: (12) 5102
1966: (10) 5107 5117
1967: (6) 5108 5114 5115 5119
1968: (4) 5101 5106
1969:
1970:
1971:
1972: (3) 5120
1973:
1974: (2) 5109
1975: (1) 5103
1976:
1977: (0) 5100

mid 1960s - This seems to have been the mass retirement. 5104 and 5105 sold to WTCo. The retirement of 5101, 5106, 5113, 5114 and 5119 were all apparently related to the use of SW8s instead on the SD&AE. 5110, 5111 and 5516 were supposed to be in CA and AZ; 5112 worked in AZ then CA (including NWP). 5118 was apparently an Oregon engine but did not have mu. Not sure where 5102 and 5108 were, maybe CA. 5107 was on NWP then in Los Angeles. 5115 total unknown as to its assignments. Besides the SDAE, there were at least nine units retired, most except 5118 probably last working in California. Of the nine, only 5102 (which had been on the SDAE a few years earlier) had mu so all the others were restricted to single engine assignments.

There is a picture of the 5118 at Albany in 1957, so it must have been working the yard or a branch there as a single unit. At least one or two of them were used out of Coos Bay on the line to Coquille and Myrtle Point until the line was cut back? Also to be considered is the mass migration of the original units out of Oregon to California. 5101 and 5102 to SDAE by Jan of 1952; 5106 in Eugene until 1963 then on SDAE by 1967; 5107 leased to NWP Oct 1952; 5108 on SDAE by Nov 1963.

1970s - 5100, 5103, 5109 and 5120 were Eugene engines and pictures can be frequently found of them on the garden tracks. There are photos of 5109 which apparently made a trip to California (San Jose and Roseville) in 1973, but it returned to Eugene well before its sale to OP&E. At least one 70T was kept for lease to WTCo if one of their units was down until SP sold them the 5100 and closed the books on the 70 tons. The last four retired all had mu.

The retirements should halfway correspond to the elimination of the jobs, abandonment or upgrade of the branches they were long assigned to.