"I will get a metallic rattling at times and it goes away when I push the shifter forward against the gate. At first I thought it was aluminum cans rattling against each other in the passenger footwell."

This sounds like a loose linkage or missing bush, as mentioned by bobo.
If wiggling the leaver helps get drive when it gives the impression its in neutral, then its likely there is a bush/linkage adjustment issue.
You havent suggested any thing that would sound like the trans is in need of a rebuild just yet!!

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I no longer question authority, I annoy authority. More effect, less effort....

1967 230-6 auto parts car. rust bucket.
1980 300D now parts car 800k miles
1984 300D 500k miles
1987 250td 160k miles English import
2001 jeep turbo diesel 130k miles
1998 jeep tdi ~ followed me home. Needs a turbo.
1968 Ford F750 truck. 6-354 diesel conversion.
Other toys ~J.D.,Cat & GM ~ mainly earth moving