You can download 9-2320-361-20, M35A2 Unit Maintenance from the Technical manuals section. It has detailed instructions with illustrations so you can get it right.
Paragraph 3-28 covers the primary filter, parts as installed from the bottom up are : washer, spring, washer, gasket, cup (cone up), filter element.
Paragraph 3-29 covers the secondary/final filters, parts as installed from the bottom up are : spring, washer, gasket, cup (cone down), cotter pin, filter element.
Attached are pics of the parts as assembled. Although the cotter pin on the secondary/final appears in the illustration to be installed below the spring, it is actually installed above the cup to hold the parts in place. Hope this helps.