See also 86-90 Oil Pump (26204-86) Individual Parts and Pics

Note: All dims are taken from a used pump (unless otherwise noted) and should be viewed as approximate measurements only.
The only intent is to show general measurements for comparison. ¹⁾

The same gear shaft part number (26488-75) was used from 77-90.
The teeth pitch are all the same on the gear.

Gear shaft pin (26430-76)
These can have slight differences in length also.
Different pins were mic'd and the dims noted as below: