Throughput accounting

Suppose production is 2000 units and sales is 1500 units.
SP is $10 and variable cost is $5 (including $1 for MATERIAL $2 for selling and distribution $1 labour cost) Fixed costs is $1000.

Income statement under marginal costing

Sales 1500×10 =$15000
Cost of sales (2000×5-500×5)= ($7500)
Contribution = $7500
Fixed costs = ($1000)
Profit= $6500 and closing inventory under marginal costing $2500.

Income statement under throughput accounting

Sales =$10
Material= $1
Throughput= $9 ×1500=13500
Fixed cost = 4×2000+1000 9000
Profit= 4500
(Confusion_ should we value fixed cost on number on units sold or produced)
I used production units as fixed costs won’t vary according to volume so full fixed costs need to becharged to income statement. But as I am concerned variable overheads are not usually production overhead. So I am confused here.
Closing inventory under throughput accounting $500. Assuming in throughput accounting closing inventory valued at material.

From all this can we deduce that if sales are lower than production than marginal costing will give more profit than throughput and closing inventory is lower in throughput accounting.

Also I know throughput accounting is not costing method but i have come across this concept while I was searching on web to deepen my understanding on throughput accounting.